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Naval Artillery

H/PJ-15, H/PJ-12 and HQ-10...

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After a long time a good thread with lot of information and knowledge. After a long time a thread that serves the purpose of this forum.

Thank you ANTIBODY. I hope this thread remains this way and is not derailed with flames and trolls.

Good work once again.
 
Wonder about the advantages relative to ´smaller, simpler´ type 730 (with similar fire controls)?

More barrels means higher RoF (?) and ... ?
 
Raytheon receives contract for advanced Standard Missile-3
by Staff Writers
Tucson AZ (SPX) Aug 09, 2013


The SM-3 does not contain an explosive warhead, but instead destroys the threats using sheer impact, equivalent to a 10-ton truck traveling at 600 mph.
Raytheon was awarded a $218,530,196 contract by the Missile Defense Agency to complete the assembly and delivery of 29 Standard Missile-3 Block IB missiles.

Launched off U.S. Navy ships, SM-3 interceptors protect the U.S. and its allies by destroying incoming short-, medium-, and intermediate-range ballistic missile threats by colliding with them in space.

"The three back-to-back successful SM-3 Block IB flight tests have demonstrated the missile's advanced capabilities and reliability against various threats in a variety of mission scenarios," said Dr. Taylor Lawrence, Raytheon Missile Systems president.

"Combatant commanders around the world are eager to build up their inventories in support of Phase 2 of the Phased Adaptive Approach starting in 2015."

Final assembly will take place in Raytheon's new, state-of-the-art Redstone Missile Integration Facility in Huntsville, Ala. Guidance sections and guidance units will be built at the Raytheon Missile Systems Space Factory in Tucson, Ariz.

"The Redstone Missile Integration Facility will prove critical as we ramp up our manufacturing capacity on the path to SM-3 Block IB full-rate production," said Dr. Mitch Stevison, Raytheon Missile Systems' SM-3 program director.

Standard Missile-3
The SM-3 does not contain an explosive warhead, but instead destroys the threats using sheer impact, equivalent to a 10-ton truck traveling at 600 mph.

More than 155 SM-3s have been delivered to U.S. and Japanese navies. Raytheon is on track to deploy the next-generation SM-3 Block IB guided missile in 2015. SM-3 Block IB will be deployed in both afloat and ashore weapons systems.
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Raytheon receives contract for advanced Standard Missile-3

Rolling Airframe Missile Block 2 completes initial fleet firing
by Staff Writers
Tucson AZ (SPX) Aug 09, 2013


RAM is a supersonic, lightweight, quick reaction, fire-and-forget missile providing defense against anti-ship cruise missiles, helicopter and airborne threats, and hostile surface craft.
The U.S. Navy completed the first fleet firing of Raytheon's Rolling Airframe Missile Block 2 as part of its ongoing developmental and operational testing (DT/OT).

In an at-sea test conducted from the USS Arlington (LPD 24), two RAM Block 2 missiles engaged a subsonic target in a scenario designed to demonstrate the advanced missile's defensive capabilities.

This test builds on three DT/OT tests conducted from the U.S. Navy's Self-Defense Test Ship earlier this year. Those firings successfully engaged both supersonic and sub-sonic maneuvering targets with all RAM Block 2 missiles meeting test objectives. The RAM Block 2 missile is now a perfect 4-for-4 in DT/OT engagements since the start of government testing.

"The first RAM Block 2 firing from a U.S. Navy ship is the culmination of a very strenuous government and industry test program," said Rick Nelson, vice president of Raytheon Missile Systems' Naval and Area Defense product line.

"We now focus on the U.S. Navy's initial operational capability milestone along with delivery of the first RAM Block 2 production missiles in 2014."

Raytheon and its manufacturing partner RAMSYS of Germany were awarded the second U.S. Navy RAM Block 2 low-rate production contract for 61 missiles in December 2012. In addition, as previously reported, Raytheon and RAMSYS received a production contract for 445 RAM Block 2 missiles from the German navy earlier this year.

RAM
RAM is a supersonic, lightweight, quick reaction, fire-and-forget missile providing defense against anti-ship cruise missiles, helicopter and airborne threats, and hostile surface craft. The missile's autonomous dual-mode, passive radio frequency and infrared guidance design provide a high-firepower capability for engaging multiple threats simultaneously.

RAM is installed, or planned for installation, aboard more than 170 ships as an integral self-defense weapon for the navies of Egypt, Germany, Greece, Japan, the Republic of Korea, Turkey, the United Arab Emirates and the United States.

The RAM Block 2 upgrade includes a four-axis independent control actuator system and an increase in rocket motor capability, increasing the missile's effective range and delivering a significant increase in maneuverability. The improved missile also incorporates an upgraded passive radio frequency seeker, a digital autopilot and engineering changes in selected infrared seeker components.

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http://www.spacedaily.com/reports/R...ock_2_completes_initial_fleet_firing_999.html
 
Gun Nomenclature

General

Naval Guns are usually classified by "caliber" (diameter of the bore), "calibers" (length of the barrel described in multiples of the diameter of the bore) and a "Model" or "Reference" designation. Some nations include a modification designation to indicate a change from the original design.

For example, the description: USN 16"/50 Mark 7 Mod 0 means that the gun was developed by the Navy of the United States of America, has a bore 16 inches (40.64 cm) in diameter, a barrel length of 16 x 50 inches = 800 inches (20.320 m) long and is the seventh version of the 16 inch gun with no modifications to the original Mark 7 design.

The way barrel length is measured may differ between nations and sometimes gun types. Please see Barrel Length / Bore Length below. Generally speaking, the longer the barrel, the more powerful is the gun.

Gun and Mounting Designations of the Major Naval Powers

British Designations

In the latter half of the 19th century, British cannon designs made a gradual transition from muzzle loading rifles (MLR) to breach loading rifles (BLR, later shortened to just BL). Any breech loader of that period which could fire faster than about two rounds per minute was known as a "quick fire" (QF) cannon, whether it used bag ammunition or cartridge ammunition. However, by the early part of the twentieth century, the BL designation was given only to bag guns while the QFdesignation was used only for cartridge guns. This separation into BL and QF categories was carried into the designation system, with BL and QF guns of the same caliber being enumerated into different numeric series. Except in gun lists, QF guns were not usually further subdivided into separate and fixed ammunition types. Gun designations during this time were per the diameter of the bore in inches or, for smaller guns, by the nominal weight of the projectile in pounds. A few guns, mainly those developed abroad, were designated by the manufacturer and the bore size in millimeters, such as the Bofors 40 mm and the Oerlikon 20 mm. The bore size was followed by the BL or QF designation and a Mark number using Latin numbers, sometimes followed with one or more asterisks or stars which indicated minor modifications to the original design. For example, the designation 4-in QF Mark XVI* meant a cartridge gun firing a 4 inch (10.2 cm) projectile, with the design being the sixteenth gun in the 4-inch QF series and having had one minor modification to the original design.

Official documents generally follow the nomenclature sequence described above. However, gun breeches were usually engraved slightly differently, with the BL or QF designation being first and then the bore size and mark number following along with a Wire or Steel designation denoting the construction method (see "Wire-Wound" and "Built-up" below). In addition, official documents for gun calibers that never had QF versions almost invariably omit the BL designation. For example, the famous 15-in Mark I is seldom shown with a BL designation, as all 15 inch (38.1 cm) guns were bag guns. Likewise, a few cartridge guns had the QF designation omitted for similar reasons, such as the 20 mm Oerlikon guns.

Many, but not all, larger-caliber weapons designed for the British Army were given mark numbers in the same series as naval guns of that caliber, a practice which occasionally leaves a "hole" in the naval mark number series. I do not usually include a data page for such Army-only weapons, but instead put a "Nomenclature Note" on an appropriate datapage to account for these "missing" mark numbers.

For guns with fractional inch bores, the British practice in official documents was to place the decimal point directly under the inch symbol followed by the tenth inch value, a combination not readily reproducible with modern type fonts. Roughly, this would appear as 4."5 for a 4.5" (11.4 cm) gun. For clarity, I show all such designations as 4.5" (11.4 cm).

Naval mountings had a separate designation, usually incorporating the type of mounting into the designation, and enumerated by the gun caliber. For example, the mounting designation 4.7-in CP Mark XIV meant that the mounting was for 4.7-inch (12 cm) guns, was a "Center Pivot" type, and was the fourteenth mounting in the CP series used for 4.7-inch (12 cm) guns. Similar to guns, asterisks were used to show modifications to the original design, with each additional asterisk identifying a separate modification. A few smaller mountings were designated by their total weight. For example, the 12-pdr 18-cwt was a designation given to a mounting for a 3-inch (7.62 cm) gun firing a 12-pound (5.4 kg) projectile and the gun and mounting together weighed 18-hundredweight or about 2,016 lbs. (914 kg).

Up until shortly after the end of World War II, British weapons were almost always known by their gun designation and not by the designation of the mountings in which they were used. For example, the designation of the 15-in Mark I was for the gun itself, not for its mounting. However, in 1950 the British weapon nomenclature system was changed such that weapons were now known by the designation of the mounting that they were used in and not by the designation of the gun itself. At this same time, Roman numerals were dropped in favor of Arabic numerals.

Some confusion was created under this new designation system as many older weapons were redesignated, even though the weapons and mountings themselves did not change. For example, the weapons used on the Daring class destroyers of the late 1940s were 4.5-in Mark V guns and these were used in 4.5-in Mark VI twin mountings. Under the old nomenclature system, these weapons were referred to as being the 4.5-in Mark V, in other words, by the designation of the gun itself. Under the new system, the guns and mountings together were now referred to as being the 4.5-in Mark 6, which had previously been just the mounting designation. In an effort to reduce confusion, both the original and subsequent designations are given on my data pages for these redesignated weapons, with the newer designations shown in parenthesis.

Under this new nomenclature system, modifications were also now given arabic numerals rather than asterisks, although asterisks were brought forward for those guns having had additional modifications after being redesignated. For example, the 4.5-in Mark IV guns and 4.5-in Mark V mountings taken from scrapped "C" class destroyers and then modified and reused on the Tribal class frigates (Type 81) built in the 1950s were now designated as 4.5-in Mark 5* Mod 2. This designation meant that these mountings had been modified once prior to the change to arabic numbers and then modified twice more after the change.

Weapons designed post-war were designated with an N (apparently for "Navy") such as the 6-in QF N5 guns used on the Tiger class cruisers in Mark 26 twin mountings.

After Britain adopted the metric system in 1965, naval guns and mountings were reclassified in metric units, although English units are still commonly used for many weapons even to the present day.

Note that none of these designation systems include barrel length (calibers) in the designation. For purposes of clarity, I have included barrel length for all gun designations on my British data pages, but strictly speaking, it is incorrect to do so.

Additional information may be found in the Naval Technical Board essay Pounders!

French Designations

Individual guns are identified by the bore in millimeters, the length in calibers of the bore and the year design was started. For example, the designation 380 mm/45 Mle 1935 (Mle = Modèle or "Model") meant a gun whose design was started in 1935, fired a 38 cm (14.96-inch) projectile and whose bore length was 38 x 45 cm long - 17.100 m (673 inches). Mountings were designated with the Model Year, for example, M1932.

Some USA weapons were in French service for a brief period following World War II, but most have been produced by France and follow the above designation system.

German Designations

The methodology of German Naval Gun designations changed three times in the first half of the 20th century. In the period before and during World War I, German guns were designated by their bore diameter in centimeters, "SK" meaning naval cannon, and their nominal overall length in calibers. So, for example, the designation 30.5 cm SK L/50 meant a naval gun firing 30.5 cm (12.008-inch) projectiles with a barrel whose overall length was 30.5 x 50 cm long - 1525.0 cm (600.4 inches). The second method was for guns designed in the period between 1920 and 1940 where the length figure was dropped in favor of the Construction Year (Model Year). For example, under this nomenclature system the guns carried by the Bismarck were designated as 38 cm SK C/34. This designation meant that these were naval guns firing 38 cm (14.96-inch) projectiles whose design was begun in 1934. The third method was adopted in 1940 and under this system guns were designated by their bore in centimeters, "KM" meaning naval cannon and the Construction Year. For example, the designation 10.5 cm KM44 was for a 10.5 cm (4.1-inch) naval gun designed in 1944.

Note that neither of these last two systems included barrel length (calibers) in the designation. For purposes of clarity, I have included barrel length for all gun designations on my German weapons data pages, but strictly speaking, it is incorrect to do so for weapons designed after 1918.

Gun Mountings were designated with the type of mounting and the Construction Year. For example, the designation Drh Tr C/25 was for a turret mounting whose design was started in 1925.

Many postwar guns are foreign designs and are commonly known by the designation given by the producing nation.

Additional information may be found in German Ammunition, Guns and Mountings Definitions.

Italian Designations

Prior to the 1920s, most large caliber guns and many smaller caliber guns were imported from Britain. For that reason, most of these guns were designed and designated in inch units. Guns developed in Italy after that time were identified by their bore in millimeters, the length in calibers of the bore and the year design was started either on the gun itself or on the mounting. For example, 135 mm/45 Model 1938 was the designation given to the guns used on the "Capitani Romani" class small cruisers and these were used in Model 1938 turrets. Often the manufacturer's name was also included as part of the designation. Mountings designed by the Italian Navy rather than by a manufacturer were given an RM designation, which stood for "Regia Marina" (Royal Navy).

Some USA weapons were in Italian service following World War II, but most post-war guns have been produced by Italian armament firms and generally follow the above designation system.

It should be noted that many Italian-produced naval guns even to the present day have been to English measurement units, not metric. For example, the main guns on the Littorio class battleships had a bore of 381 mm (15.00 inches), not 380 mm (14.96 inches) as did their French and German contemporaries. Likewise, the modern-day 76 mm Compact has an actual bore of 76.2 mm (3.00 inches).

Japanese Designations

The formal gun designation dating from the beginnings of the Imperial Japanese Navy was made up of the barrel or bore length in calibers (kôkei), a type or year type (shiki or nen shiki) which was based upon the original design date of the breech mechanism, the bore diameter and finally the suffix hô (gun). For example, the designation 40 kôkei 11 nen shiki14 cm hô (40 caliber 11 Year Type 14 cm Gun) would mean a 14 cm/40 (5.5 inch) gun whose breech design was initiated in the 11th year of the Taishô regnal era (1922 A.D.). Imported weapons had an additional designation to indicate the manufacturer.

Following the methodology of their British mentors, bore length was measured starting from the top of the mushroom head (vent axial) of the breech block for bag guns and starting from the inner breech face for cartridge guns. For a few guns, the bore length designation was actually the overall length of the barrel rather than the bore length. Unlike the British, the Japanese did not separate guns of the same caliber into bag and cartridge types.

Prior to 5 October 1917, the bore diameter was measured in English units. Guns with fractional inch bores followed British practice and were designated such as 4 in 7 (4.7 inch - 12 cm) and 5 in 5 (5.5 inch - 14 cm). For clarity, I list these as decimal values, in these instances as 4.7" (12 cm) and 5.5" (14 cm). On 5 October 1917, the Japanese Navy converted to the metric system and most naval guns were then designated with the bore diameter rounded up or down to a whole centimeter number, but not necessarily to the nearest value. For example, 3.0-inch guns were designated as 8 cm rather than 7.62 cm and 16.1-inch guns, originally designated in 1917 as 41 cm, were redesignated in 1922 as 40 cm. However, 5.0-inch guns were designated "correctly" as 12.7 cm rather than "incorrectly" as 13 cm. This may be a good place to note that anyone seeking consistency in Japanese ordnance designations is doomed to disappointment.

The shiki and nen shiki designations (Type and Year Type, which can be considered as being somewhat analogous to a Model Year) are quite complicated. On 25 December 1908, which was the 41st year of the Meiji regnal era, all guns in service in the Imperial Navy were redesignated. Weapons that had been manufactured by the Japanese were designated as 41 shiki hô (41 Type gun or Model 1908) even though most of them had been designed and produced prior to 1906. Guns developed after this time were assigned Year Types based upon when the design of the breech mechanism was begun. Two different calendar systems were used to define the Year Type. Between 1908 and 1927, the Year Type was based upon the year of the current regnal era, followed by the suffix nen (year), such as 11 nen shiki (11 Year Type or Model 1922). Those guns produced between 1927 and 1939 were assigned Year Types using the last two digits of the Imperial Calendar year, which dated from the start of the reign of Emperor Jimmu in 660 B.C., with 1927 A.D. being Imperial Calendar Year 2587. Finally, under the Imperial Calendar system, weapons designed between 2600 and 2605 (1940-45) were designated by using just the last digit of the Imperial year.

The dates in these Type and Year Type designations should be used with caution, as they are not directly equivalent to a Model Year and in fact usually only reflect the date of the first gun design in the series. There are examples of guns with the same Year Type designation having been designed many years apart, especially in the 11 nen shiki (11 Year Type) series. These designations should be looked at as being more equivalent to a "class of weapon" designation rather than as being an actual design date.

It should also be noted that these Japanese Year Type designations do not translate well into English. For example, although a literal translation of 11 nen shiki hô would be 11 Year Type Gun, this sounds "wrong" to English-speakers. For that reason, most English translations of this designation would show it as either 11th Year Type or as Type 11. Neither of these are literally correct translations, but sound "better" to English-speakers. On my data pages, Japanese designations are shown such as 11th Year Type for regnal-era calendar guns and such as Type 94 for Imperial Calendar-era weapons. As noted above, neither of these are literally correct, but I believe them to be more easily understandable by English speakers and better indicate the era in which they were designed.

On my data pages, the Year Type in A.D. is always noted and all known designations that a weapon had during its design and service life are listed.

The gun barrels themselves were designated with a numbering system somewhat similar to the USN Mark and Mod system (see below). The earliest barrel design was designated as Roman numeral I, later minor modifications were given numeric subscripts such as I2, I3, etc. Major changes to the design were given higher Roman numerals, such as II, III, etc. On my datapages, these barrel designations are usually shown such as Model Type I2.

It should be noted that the Japanese Model number system became chaotic towards the end of World War II. New weapons were assigned Year Type designations that had no relationship to the actual date of design, with some apparently chosen simply to fill in missing years in the series. As John Campbell put it, "such are the pitfalls of Japanese ordnance [nomenclature]."

As examples of Japanese designations for naval guns:

  • Japanese-built versions of the Armstrong Elswick 8"/45 (20.32 cm) guns were redesignated on 25 December 1908 as 45kôkei 41 shiki 8 in hô - 45 caliber 41 Type 8-inch gun or 8"/45 (20.32 cm) Model 1908, although the first guns were produced at the Kure Navy Yard in 1902. These guns were redesignated on 5 October 1917 as 45 kôkei 41 shiki 20 cm hô - 45 caliber 41 Type 20 cm (7.87-inch) gun, although their bore remained unchanged at 8.0-inch (20.32 cm).
  • Under the regnal era and english measurement systems, the Japanese-built 14-inch guns carried by the Kongo class were originally designated as 45 kôkei 41 shiki 14 in hô - 45 caliber 41 Type 14-inch gun or 14"/45 (35.56 cm) Model 1908, although the original design by Vickers dated from 1910 and no guns were produced in Japan before at least 1912. They were then formally redesignated in metric measurment units on 5 October 1917 as 45 kôkei 41 shiki 36 cmhô - 45 caliber 41 Type 36 cm guns or 36 cm/45 (14.17-inch) Model 1908 - even though the bore size remained the same at 35.56 cm (14.0-inch).
  • Under the Imperial Calendar system, the AA guns carried by the Agano class cruisers were designated as 60 kôkei 98nen shiki 8 cm hô - 60 caliber 98 Year Type 8 cm gun or 8 cm/60 (3.15-inch) Model 1938. However, these guns actually had a bore size of 7.62 cm (3.0-inch).
  • The British 2-pdr gun made by Vickers and exported to Japan in the 1930s was designated as 62 kôkei 91 nen shiki 40 mm "HI" - 62 caliber 91 Year Type 40 mm "HI" or 40 mm/62 "HI" Model 1931, where "HI" (also translated as "BI") was the designation meaning Vickers. This designation is notable for using the overall barrel length rather than the more common Japanese method of being per the bore length, which was 39 calibers, identical to other Vickers 2-pdr. guns.
Mountings were given gata (Model) letter designations with A being the first designation. Minor modifications to the original design were given numeric designations such as kai 2 (Modification number 2) and major modifications were given higher letters such as B, C. For example, the designation for a mounting of the second model type with two minor modifications would be B gata kai 2. For simplicity, on my data pages a mounting with this designation would be shown as B2.
Postwar guns are primarily foreign designs and are commonly known by the designation given by the producing nation.

Weapon systems other than naval guns were primarily designated as to when they entered service. For example, the famous Zero fighter plane of World War II derived its name from its designation, Type 0 carrier-based fighter, as its service introduction was in the Imperial Calendar year 2600 (1940).

Additional information may be found in Japanese Ammunition, Guns and Mountings Definitions.

Russia / USSR Designations

Prior to 1917, designations included the bore size, overall barrel length and the Obrazets - Pattern (Model) Year. Guns were designated either by their caliber in inches if it was a whole number or in millimeters for all others. The Pattern Year was the date the weapon was accepted into service. After 1917, a project number was added and all calibers were designated only in millimeters. As an example of the post-1917 designation system is 130 mm/50 B13 Pattern 1936, which meant that this was a weapon firing 130 mm (5.1-inch) projectiles, had a barrel 50 calibers long, was designed at the "Bol'shevik" plant as Project 13 and which entered service in 1936.

United States of America Designations

Up until just after World War II, each caliber of USN guns was identified by its length in calibers, a mark number and a modification number, the original modification designation being "Mod 0". For example, 16"/50 Mark 7 Mod 0 meant a gun firing 16-inch (40.64 cm) projectiles with a barrel 16 x 50 = 800 inches (20.320 m) long, was the seventh gun in the 16-inch (40.64 cm) series and was built to the original design with no modifications. A few smaller guns built or purchased mainly in the latter part of the 19th century were known by the weight of their projectiles; the 1-pounder through 6-pounder. Roman numerals were used for Mark designations until about 1920 when arabic numerals were substituted.

Gun Mod numbers generally indicated changes to the original design for new guns or a change made to a finished gun. For example, a change in the rifling pattern from the original design might be designated as Mod 1 and new guns built with this rifling would be so designated. Guns more heavily modified would be given new Mark numbers, such as the 14-inch (35.56 cm) Mark 4 guns rebuilt during the 1930s and then redesignated as Mark 11 guns.

Mountings originally had a similar designation, being of the form 12" Mark 8 Mod 0 for a mounting using a 12-inch (30.5 cm) weapon. By 1930, the Mark number mounting designation had been dropped for weapons larger than 5 inches (12.7 cm) and new mountings were then known by the ship class they were used on. For example, the mountings for the 16"/50 (40.64 cm) Mark 7 guns used on the Iowa class battleships were designated as 16-inch three-gun mountings Iowa class. Mountings for 5 inch and smaller guns continued to have Mark numbers assigned to them.

Similar to Britain, shortly after World War II the USN designation system was changed from being based upon the gun classification to being based upon the mounting classification. So, a modern designation such as 5"/54 Mark 45 is really the designation of the gun mount, not the weapon itself. Furthermore, starting with the 5"/54 Mark 42, almost all naval guns are now classified into a single "Mark" series, regardless of their caliber. For example, modern guns such as the 5" Mark 45, the 76 mm Mark 75 and the 57 mm Mark 110 are all in the same numeric Mark series.

Additional information may be found in USN Naval Gun Designations.



Bag Ammunition" on the Ammunition Definitions data page for additional information.

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Bayonet Joint - An interrupted-thread method of attaching the gun barrel to the housing in order to make for easier barrel replacements. For many USN guns designed for case ammunition, the housing took the place of the yoke and screw-box liner used on bag guns. This construction method allowed the elimination of the slide cylinder in some weapons.

Barrel Length / Bore Length - One of the more confusing items about gun designations is that the way that the length (calibers) of a gun barrel is measured differs from nation to nation. The USA measured starting from the inner breech face for both bag and cartridge guns. Austria-Hungary (Skoda), Germany and Russia measured the length of the entire barrel. Britain, France, Italy, Japan and Sweden (Bofors) measured starting from the top of the mushroom head (vent axial) of the breech block for bag guns and starting from the inner breech face for cartridge guns. These differing methods have often resulted in nomenclature errors in reference works. For example, the 38 cm SK C/34 guns on the German battleship Bismarck are often noted as being 47 calibers long. Per the German method - overall barrel length - these guns were 51.66 calibers long and per the British/USA method - measured from the inner breech face - they were 48.3 calibers long. As every German document I have seen refers to these guns as being the equivalent of either 51.66 or 52 calibers long, I am not certain why so many authors refer to these guns as being 47 calibers long. My thanks to M.J. Whitley, whose series of books on German Warships of World War II first enlightened me on how the German methods differed from those of other nations. On my webpages, "Gun Length oa" refers to the overall barrel length. "Bore length" is per each nation's specification except where noted.

BL - British designation meaning Breech Loading cannon. In the 1800s the the British used the designation BLR where the "R" stood for Rifle, but after about 1890 the "R" was dropped from new gun designations. By the early part of the twentieth century, BL had become to be used only for bag ammunition guns.

BM - Breech Mechanism.

BMG - Browning Machine Gun. These were recoil-operated machine guns of various calibers originally designed by the USA inventor John Moses Browning (1855 - 1926), the most famous being the "fifty-caliber." The modern version is the0.50" (12.7 mm) BMG M2HB, with M2HB meaning Mark 2 Heavy Barrel. The M2 designation is why this weapon is often known as the Ma Deuce.

Bolt - The mechanism that positions the cartridge in breechloading guns, closes the breech, and ejects the spent cartridge case.

Bolt Open or Open Bolt - Refers to automatic or semi-automatic weapons that are designed such that the gun bolt is normally held to the rear of the weapon, leaving the breech open. Only after the trigger is activated is the next round pushed into the firing chamber and the breech closed. This design reduces the chances of an accidental "cook off" as no bullet is in the firing chamber until after the trigger is activated.

Bolt Closed or Closed Bolt - Refers to weapons that are designed to hold a bullet in the firing chamber with the bolt closed prior to activating the trigger.

Bore - Inner Diameter (ID) of the barrel. This is measured from land surface to diametrically opposed land surface. For example, the USN 16"/50 (40.64 cm) guns used on the Iowa class battleships had a new gun land to land diameter of 16.00 inches (40.64 cm) while the diameter as measured from the bottom of the groove to the opposite bottom of the groove was 16.30 inches (41.40 cm). "Bore" is also used as a shorthand reference for "Bore Length" - see "Barrel Length / Bore Length" above.

Bore, Squeeze - The bore near the muzzle is slightly reduced in diameter in order to better center the projectile before it leaves the gun. This reduction also flattens out the driving band, thus giving the projectile a better aerodynamic shape. For a related design, see "Probertised" below.

Breech - The rear of the gun. In most 20th century guns, where the shell goes in, hence the name "Breech Loader."

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Breech Block, Breech Mechanism or Breech Plug - This is the mechanism at the rear of the gun which closes the bore against the force of the firing charge. For large weapons, such as a battleship's main guns, these are usually of an interrupted-screw construction, which gives a very strong seal. For rapid fire guns, a sliding breech-block is commonly used which may open and close automatically as the gun is fired.

Breech, Four-Motion - Early screw breech design invented by the French where all of the threads were at the same level. Usually there were five or six threaded sections separated by equal width non-threaded sections. These breech blocks were comparatively long as half of the thread was cut away to allow withdrawal, thus reducing their capacity to withstand firing stresses. This type of breech mechanism required that the block be first withdrawn straight back from the gun barrel before it could be moved out of the way of the reloading process and some had to be disconnected entirely from the gun. Closing the breech was a complicated operation, involving four motions: swing the carrier so that the screw could enter the breech, slide the entire breech mechanism forward so as to seat it, turn the screw through part of a turn until the threads meshed with those in the breech, and then lock the mechanism.

Breech, Holmstrom - A type of breech mechanism for bag guns whereby the screw block was operated by a crank that moved parallel to the rear face of the block. Named after the inventor, Carl Holmström.

Breech, Pure-Couple - British Welin Breeches of the early 1900s that used a long, manually operated lever to operate the breech screw. A "couple" consists of two parallel forces that are opposite in direction and do not share a line of action. A couple does not produce any translational movement, only rotation. A "pure couple" always consists of two forces that are equal in magnitude. So, a "pure couple breech mechanism" is one that uses and produces rotational force in order to work the breech plug. See "Breech, Welin" below.

Breech, Single-Motion - See "Breech Mechanism, Smith-Asbury" below.

Breech, Three-Motion - Similar to a Four-Motion Breech, except that the breech was withdrawn into a hinged carrier ring. This meant that the motions were reduced to unlocking, withdrawal and then swinging out of the way.

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Breech, Welin - A stepped-thread breech developed during the 1890s and named after the inventor, Axel Welin, a Swedish Ammunition Engineer then residing in London. A Welin breech block has only one third or one quarter of the threads removed, which means that a shorter screw length can be used to obtain the same strength as a four-motion breech mechanism. See the "breech plug" in the illustration above for a typical Welin design. Unlike the four-motion breech, a Welin breech allows the mechanism to be simply unscrewed and swung out of the way, it does not have to be withdrawn straight back from the gun barrel. Variations of the Welin Breech design were used on most bag ammunition guns of the twentieth century.

Breech Block, Vertical Sliding-Wedge - Used on many cartridge guns, this sort of breech mechanism slides vertically in grooves cut in the housing. After the cartridge is inserted, the breech block slides up with the sloping part of the forward face wedging the cartridge home in the chamber. An extractor mechanism catches the cartridge case rim as the breechblock drops after firing, pulling the expended cartridge case out of the gun. A few guns use a similar design, but with the breechblock sliding horizontally. These, of course, are known as "Horizontally Sliding-Wedge" breechblocks.

Breech Mechanism, Smith-Asbury - Introduced in 1916 and named after its inventors, Lt. Cmdr. George Leonard Smith, USN and Draftsman Dorsey Frost Asbury, both of the Naval Gun Factory at the Washington Navy Yard. This mechanism used gearing to fully open a Welin breech by linking the unscrewing, withdrawing and swinging clear movements into one continuous action and for that reason is sometimes known as a "single motion" breech mechanism. The breech threads are undercut at the start so as to allow the block to swing into position.

Built-up Construction - Guns that are manufactured from multiple hoops (tubes) which are joined together with locking rings and overlapping sections to make longer and/or thicker sections. This was the most common process for manufacturing almost all guns until the 1920s when monobloc techniques were introduced for guns smaller than about 6 inches (15.2 cm). See "Monobloc" and "Wire-Wound" below.

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Caliber and Calibers - "Caliber" refers to the bore diameter of the gun barrel or to the diameter of the projectiles fired. "Calibers" refers to the length of the gun barrel in multiples of the projectile diameter.

Cartridge Guns - Weapons in which a metallic container, usually brass or steel, is used to hold the propellant. Most commonly used for "Quick Firing" and automatic weapons.

Chamber - Part of the gun in which the propellant charge is placed. In a bag gun, that space between the obturator or breechblock and the forcing cone. In fixed or semi-fixed ammunition, the space occupied by the cartridge case.

Chamber, Fluted - Small longitudinal channels cut in the chamber walls, used in many semi- and fully-automatic weapons. When the cartridge is fired, these channels allow a small portion of the propellant gases to get between the cartridge case and the chamber walls, preventing the cartridge case from "sticking" to the chamber walls, thus making it easier to extract.

Chamber Size - Space available for gas expansion when the projectile is seated in position; measured from the face of the closed breech block, around the base of the projectile, to the rear of the rotating band (or obturator). In fixed ammunition, it is the volume of the cartridge case behind the projectile.

Chrome Plating - In the 1930s, the USN started to chrome plate the bores of most guns to a depth of 0.0005 inches (0.013 mm). This was "hard chrome," which is not the kind that you find on your father's Oldsmobile. This plating increased barrel life by as much as 25%. The plating generally extended over the length of the rifling and shot seating. Chrome plating has also been found to reduce copper deposits.

CIGS - Close In Gun System. A weapon system designed to combat small boats at short ranges - the "Boghammer" threat.

CIWS - Close In Weapons System. A weapon system designed to combat anti-ship missiles or aircraft at short ranges.

Cup Obturation - I cannot possibly improve upon Mr. Ruffell's description (Off-Site at Royal New Zealand Artillery Comrades Association).

cwt - Hundredweight. British unit of measurement that was used to designate smaller weapons by the weight of the gun and mounting. One hundredweight is 112 pounds (50.8024 kg).

De Bange Obturator System - See "Obturator" below.

DEF - Direct Electric Firing, usually abbreviated as "E." British gun prefix designation meaning that the gun was fired by electric arcing.

DP - Dual Purpose. These guns are intended to be used against both surface and aircraft targets. Maximum elevation of these guns is usually greater than 50 degrees.

EMF - Electro Mechanical Firing, usually abbreviated as "F." British gun prefix designation meaning that the gun was fired by electromotive force, i.e., a solenoid activating a striker pin.

EFC or ESR - A means of estimating the remaining accuracy life of a weapon. Accuracy life for a gun or liner is usually expressed as "EFC" meaning Equivalent Full Charges or as "ESR" for Equivalent Service Rounds. On my webpages, this is the number specified. A gun or liner has reached the end of its accuracy life when the projectiles and propellant charges assigned for its use give range patterns that exceed an arbitrarily adopted size, generally something like 10 percent larger than those with a new barrel. For large caliber guns, life is roughly the same as the number of AP shells that can be fired with full charges before the barrel needs to be replaced or relined. Compared to rounds fired with full charges, Practice Rounds and shells fired with reduced charges generally cause less wear, while proof charges and super charges cause more wear. The amount of wear immediately forward of the origin of the rifling is the most important value used in determining the remaining life. The three main causes of bore erosion are thermal stress, mechanical wear and chemical erosion. The greatest source of wear is from the propellant gasses, which corrode the rifling via heat and chemical action.

FER - Fatigue Equivalent Rounds. The mechanical fatigue life of a gun barrel or liner expressed as the number of mechanical cycles the gun barrel or liner can withstand before needing to be replaced. This has replaced EFC/ESR for some modern weapons.

Firing Lock or Primer Chamber - A feature of the breech mechanism used for bag guns, this is a small enclosure into which the igniter or primer is inserted. See "Primer vent or vent axial" below.

FLAK - FliegerAbwehrKanone. German designation for AA weapons (FLAK guns). Literally means "Flier Defense Cannon." During World War I, this term was used by Allied airmen to describe the shell bursts from such weapons, which has become the current accepted meaning of the term.

Forcing Cone or Seat - The forward end of the gun chamber where it necks down to the start of the rifled portion of the barrel. This guides the projectile as it is being rammed.

GAU - US Military designation for airborne guns and gun systems.

Grooves - A rifled gun is so called on account of the spiral grooves which are cut into the surface of the bore and into which the soft metal projectile driving bands are forced during its travel down the bore. See "Rifling" and "Twist" below.

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Grooves, Plain-Section - A rifling pattern where the bottom of each groove is concentric with with the bore and the sides of which terminate in a small radius.

Grooves, Hook-Section - A rifling pattern which has a "driving" side which exerts a high pressure on the projectile driving band while the other side of the groove has a gentler slope which exerts little pressure on the driving band. In a gun with RH twist, the driving side is on the right hand side.

GWS - Gun Weapon System.

HA - High Angle. British designation used to denote DP or AAA guns or directors. Meant that the gun could be elevated past about 50 degrees or that the director was intended for AA use. Replaced by "AA" in 1947.

HA/LA - High Angle/Low Angle. British designation of World War II equivalent to DP. Meant that a gun or director was intended for use against both surface and aircraft targets. This designation was replaced by AA/Su (anti-aircraft/surface) in 1947.

Hoop or Tube - A section of the gun barrel. See "Built-up Construction," "Monobloc Construction" and "Wire-wound Construction."

Hornrings - Rings shrunk onto German heavy guns to which the piston rods of the recoil and run-out cylinders were attached.

IV - Initial Velocity. Velocity of the projectile upon leaving the barrel of the gun. Equivalent to "Muzzle Velocity."

KM - Kanone Marine. German for "Naval Cannon." Usually followed by the model year. For example, KM42 meant a naval gun designed in 1942. This designation system was used for some guns designed between 1940 and 1945.

LA - Low Angle. British designation used to denote SP guns or directors. Means that they are intended for use solely against surface targets. Replaced by "Su" for surface in 1947.

Lands - The bore surface between rifling grooves inside the gun barrel. See "Rifling," below.

Life - See "EFC or ESR," above.

Liner - A replaceable tube within the gun barrel. The useful life of a gun is measured by how much rifling remains. By having the rifling milled into a replaceable liner, the life of the gun barrel itself is increased by many times. A "Loose Liner" or "Loose Barrel Construction" means that the gun was built with a small clearance between the outer diameter of the liner and the inner diameter of the next outer part. When firing, the gas pressure elastically expands the liner but otherwise the clearance remains. This method of construction makes it easy to replace the liner after removal of the locking devices. The replacement method for standard liners is much more complicated. The USN used a "gun pit" into which the barrel was lowered. Heat was then applied to the outside of the barrel while cold air was pumped through the bore. The result was that the barrel expanded while the liner contracted, thus opening a small clearance around the liner. The liner could then be extracted from the barrel. Liners are usually coated with graphite in an effort to ease assembly and disassembly.

Locking Ring - A short cylindrical casting used for joining gun barrel tubes together. See "Hoop" above.

MG - Machine Gun.

MK or Mk - Abbreviation for "Mark."

MLR - British designation meaning Muzzle Loading Rifle.

Monobloc Construction - A gun built from a single tube apart from the breech-ring and breech mechanism rather than a multi-tube built-up design. During the 1920’s, when centrifugal spun castings came into being, it became possible to make cylindrical castings with a precise wall thickness and density with no cracks. The inside diameter of these spun castings could be controlled to the point where very little machining had to be done to true-up the inside diameter. The general process was to make three tubes; the gun barrel itself, the breech ring and a liner, which together made up the gun barrel. These three tubes were assembled onto each other, usually by autofretting techniques, with the breech ring making a thicker and thus stronger section at the breech end of the gun. Later designs for guns smaller than about 6 inches (15.2 cm) further simplified the manufacturing process by eliminating the separate liner. Monobloc construction makes for a straighter, stronger barrel than does built-up construction and overcomes some of the problems with having to make one solid casting with a thickening at the breech. This older style of casting had cooling problems due to the uneven wall thickness which could lead to cracks developing.

Mushroom head - A component of Welin breech-blocks, this is the forward part of the breech-block, between the chamber and the obturator. See the diagrams for the "Breech-block" and "Obturator."

Muzzle - The fore or "Business End" of the gun. Where the shell comes out.

Muzzle Bell or Swell - Many guns have a barrel thickening at the muzzle. This is meant to strengthen the gun barrel at the muzzle and so prevent the guns from splitting. This feature is also known as the muzzle "tulip", "lilly" or "flare." Modern weapons use higher quality steel and so lack a bell, or instead have lugs, which are utilized when the liner is replaced (the lugs serve to anchor the tool used for pulling the liner out).

Muzzle Brake - A device on the muzzle which diverts part of the propellant gasses to the sides or rear in order to reduce the recoil force.

Muzzle Droop - As in any unsupported structure, a gun barrel bends due to the action of gravity. The vertical distance that the muzzle end of a gunbarrel moves from its "ideal" position is called droop. Gun barrels are usually orientated in their mountings in the direction that produces the least amount of droop.

MV - Muzzle Velocity. The velocity of the projectile as it leaves the gun barrel. Equivalent to "Initial Velocity."

Nendo Shiki - Japanese for "Year Type." See "Japanese Designations," above.

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Obturator - For breech loading guns, this is a device for making the breech gas-tight, preventing any escape of propellant gas while the breech is closed. For bag guns using Welin breech blocks, the De Bange obturator system (named after Captain de Bange of the French Army, who invented it in 1872) was commonly used. The De Bange obturator system consists of a doughnut-shaped washer pad, also known as a "gas check pad," that is located between the mushroom head and the screw breech. See the breech illustrations for details. When the breech is closed, rotating the screw squeezes the pad against a conical section of the gun barrel. When the gun is fired, the mushroom head is driven back against the pad which forces it tighter into the conical seating and thus seals the barrel. For guns using cartridge ammunition, the cartridge case itself becomes part of the obturator system. Generally speaking, both the cartridge case lip and cartridge case mouth are used to seal the barrel. The cartridge case lip is forced tightly against the breech when closed while the chamber of the gun is designed such that the expansion of the mouth of the cartridge case when the gun fires helps to seal the barrel. Also see "Obturator" underProjectile Definitions.

Pdr. - A way designating weapons in terms of the weight of the projectile they fired. For example, the British 2-pdr. AA gun fired a shell weighing about two pounds (0.9 kg). For reasons that can only be described as traditional, the British, alone of all modern nations, clung to this method of designation well into the twentieth century, long after other nations had switched to designating weapons by their bore diameter.

Pom-pom - This term originated with the British 1-pdr. used during the Boer War and was later applied to the 2-pdrs. of World War I and II. Reportedly, this was the sound made by large automatic guns when firing.

Primer Channel - See "Firing Lock" above.

Primer Vent or Vent Axial - A feature of the breech mechanism used for bag guns, this is a hollow tube running from the firing lock or primer chamber through the stem to the front of the mushroom head. When the igniter or primer is fired, it generates a flame which travels through this tube into the propellant charges. See the above obturator illustration.

Probertised - A gun barrel where the rifling grooves near the muzzle gradually disappear until the last section of the barrel becomes smoothbored. When a projectile travels through this section, its driving bands get flattened against the shell body, giving the projectile a smoother shape and thus improving its aerodynamics. Named after the inventor, British Colonel Probert of the Woolwich Arsenal.

QF - British designation meaning Quick Firing cannon. In the late 19th and early 20th centuries, this term was used to define any gun that could be fired several times per minute whether it used bag or cartridge ammunition. By the 1920s this designation was given only to guns that used metallic cartridge cases.

QFC - Quick Firing, Converted. Early British Bag guns modified to use cartridge cases.

Receiver - The main portion of the weapon, to which the barrel and operating mechanism are attached.

Rib-Rifling - Rifling pattern where the grooves are very wide and the lands are very narrow. Lands are known as Ribs for this kind of rifling.

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Rifling - The bores of most gun barrels have grooves milled into them in a spiral pattern. These grooves engage the Driving Bands on the projectiles and thus impart a spin to them as they leave the barrel. Spinning the projectiles makes them more stable in flight which greatly increases their accuracy and range. It also makes them more likely to land nose first, which is very important for an armor-piercing shell. The way the grooves are milled varies greatly. Some manufacturers prefer a uniform pattern, others prefer grooves that vary in depth and width as they progress through the weapon. See "Twist" below.

RF - Rapid Fire. USN term equivalent to QF during the end of the 19th century and first half of the twentieth century. At the end of World War II, this term was used to describe large caliber guns with automatic shell-handling equipment such as those carried by the USS Des Moines (CA-134) class heavy cruisers.

ROF - Rate of Fire. Usually shown in terms of RPM - Rounds per Minute. ROF may be affected both positively and negatively by many different elements, too numerous to list here. ROF figures given on my data pages for manually-operated guns represent nominal values and should not be interpreted as being literally correct under all circumstances. ROF figures on my data pages for automatic weapons are usually the cyclic values, with practical values given where possible. It should be noted that an air-cooled automatic or semi-automatic gun can be fired continuously at its maximum cyclic rate for only a short period, otherwise its barrel will start to soften or melt. Automatic guns using a water jacket, especially those with a recirculation method including a radiator, may fire continuously at their maximum cyclic rate for much longer periods, as the cooling water helps to keep the barrel below the melting point.

rpgpm - Rounds per gun per minute. The rate of fire of each gun in a multiple gun mounting.

RPM - Rounds per Minute. On my data pages for multiple gun mountings, this is always listed in terms of rpgpm.

Screw box liner - The barrel sectional casting to which a screw breech block screws into when closing. Known as the "breech bush" in British weapons.

Sear - Holds the firing pin in a cocked position against the compression of a spring until the trigger is activated, which allows the spring to drive the firing pin into the primer.

Separate Loading - See "Bag Guns" above.

SF - Slow Firing. This may not have been an official designation, but instead may have been a way of differentiating those guns that were not "QF" or "RF" types.

SK - Schnelladekanone or Schnellfeurkanone. German for "Fast Firing Cannon," equivalent to QF or RF. Also listed as being for "Schiffskanone" or "Ship Cannon." See "German Designations" above.

Slide cylinder - The part of the gun forward of the rear cylinder which fits in the slide and moves through it during recoil. Keys are usually inserted between the slide and the slide cylinder to prevent rotation of the gun due to the reaction of the projectile on the rifling. See "Slide" below.

Smoothbore - A gun barrel or gun barrel section that does not have any rifling.

SP - Single Purpose. Means that the weapon is intended for use only against surface targets. Maximum elevation of these guns is usually less than 45 degrees.

STAAG - Stabilized Tachymetric Anti-Aircraft Gun.

Su - Surface. British designation for SP guns. This replaced the previous "LA" in 1947.

Stabilized - When a mounting is referred to as "stabilized," it means that it contains some method for correcting for the deck inclination caused by the rolling and pitching of the ship. Usually, this involves more than two axis of motion (traverse, elevation) and requires gyroscopes.

Striker Gear - The firing pin and associated mechanisms used in percussion firing.

Tampion or Tompion - A plug that goes into the muzzle of the gun. Keeps the sea spray out of the barrel. In the USN, pronounced "tom-kin."

Taper wound or Taper winding - British method of wire-wound gun construction in which a single length of wire is used rather than multiple lengths. Introduced following World War I. See "Wire-wound Construction" below.

TBK - Torpedoboots Kanone. German for "Torpedo Boat Cannon." Also shown as Tbts K.

Trunnion - The cylinders upon which the gun barrel pivots up and down.

Tube - Gun barrel section. See "Built-up Construction," "Monobloc Construction" and "Wire-wound Construction."

Twist - Rifling grooves make a spiral towards the gun muzzle. The length of the barrel necessary for the grooves to make one complete revolution is called "Twist." This is usually expressed in calibers but sometimes appears in measurement units (inches or meters). On my data pages, Twist is specified in calibers, with "RH 1 in 25" meaning that, when looking at the top of the barrel from the breech end of the gun, that the spiral goes in a right-hand direction and that it takes 25 calibers for the grooves to make one complete revolution. Depending upon the internal ballistics desired, the spiral may be of a uniform pattern, where the angle of inclination remains constant throughout the bore, or it may be of a parabolic pattern with the twist increasing as it nears the muzzle. The steepness of the twist is related to the length and weight of the projectiles fired. Twist is intended to make a projectile spin at a stabilizing rate as it exits the barrel. Generally speaking, a longer, heavier projectile must spin faster than a shorter, lighter projectile in order to remain stable in flight. As a rule of thumb, a projectile fired from a smaller caliber gun spins close to 100% of the rate determined by the muzzle velocity divided by the twist length. By contrast, due to slippage caused by inertia, large-caliber projectiles spin at about 90% of the rate determined by the muzzle velocity divided by the twist length. As an example of calculating spin rate, for a 16 inch (40.64 cm) gun with a uniform twist of 1 in 25, the barrel length required for the twist to make one full rotation would be 16 x 25 = 400 inches or 33.33 feet (10.16 m). Nominally, this twist would mean that a projectile with a muzzle velocity of 2,500 fps (762 mps) would be rotating as it left the muzzle at about 75 RPS or 4,500 RPM, but because of slippage it is actually rotating at about 67.5 RPS or 4,050 RPM. Because of gyroscopic and corolis effects, a shell fired from a gun with RH twist will tend to drift to the right while one fired from a gun with LH twist will drift to the left. Drift due to the corolis effect is near zero at the equator and at its maximum at the earth's poles. The amount of drift is also affected by the direction of fire. Fire control systems have input settings for the ship's latitude and the direction of fire so as to correct for these effects. Note: I have never found a naval cannon with LH twist, they all have RH twist. I have found a few small-arms that use LH twist, including the famous Colt black-powder pistols of the mid-1800s, but most small-arms use RH twist.

UBK - Untersee-Boots Kanone. German for "U-boat Cannon." Also shown as "Ubts K."

Water-cooled - A weapon which uses a water-jacket around the gun barrel. These are used on machine guns and rapid-fire weapons in order to keep the barrel from softening or melting during prolonged firings. The development of higher-quality alloys in recent years has reduced or eliminated the need for water jackets on many newer weapons.

Wire-wound Construction - A method of strengthening built-up gun barrels by using long lengths of wire wrapped around an inner tube. This method of construction was used extensively by the British roughly between 1880 and 1925. Few nations other than Japan adopted this technique as it greatly complicated the manufacturing process. The wire was about 0.1 inches (2.5 mm) thick and had a rectangular cross-section or was sometimes ribbon-shaped. The wire was quite strong with tensile strengths of up to 200,000 psi (14,000 kg/cm2) and very long lengths of wire were used. For example, the British 15-in/42 Mark I used about 170 miles (274 km) of wire on top of the "A" tube. A "B" tube was then shrunk on overtop the wire-wound section. It should be noted that wire-winding strengthened the gun barrel only in regards to resisting the gas pressure generated by the burning propellant. There is some controversy as to whether or not this type of construction weakened the overall barrel strength and increased the amount of muzzle droop. The British gradually replaced wire-winding construction with monobloc and built-up construction techniques and by 1930 no longer used it all. The last Japanese weapon using wire-winding was the 46 cm Type 94 guns used on the Yamato class battleships.

Working Pressure - The pressure generated inside the barrel by the burning propellant. This pressure is measured at the breech of the gun. Because of the pressure gradient in the barrel, the peak pressure at the base of the projectile is at a smaller value. A reasonable rule of thumb is that the pressure at the breech is between 1.16 to 1.2 times greater than the pressure seen at the base of the projectile. It should be noted that the pressure values found in reference works for older guns are not particularly accurate. Pressure was measured by the size of a copper cylinder that was crushed when the gun was fired. The size of the cylinder crushed was converted to "copper units of pressure (CUP)." Historically, the chamber pressure for U.S. Naval guns has been specified in long tons copper per square inch (tsi). To convert to true pressure, the copper tsi is multiplied by 2.688 to get pounds per square inch (psi). The copper cylinder method has been made obsolete by the invention of piezoelectric strain gauges which have made pressure measurements much more precise. Copper tubes are still used by both the US Army and Navy for tests where only peak pressure testing is required, such as for barrel proof or ammunition lot acceptance. Modern smaller caliber guns are usually rated in terms of psi (pounds per square inch) or MPa (megapascals).

Yoke - The large ring surrounding the breech end of the barrel which provides a connection between the barrel and the recoil system. Shoulders on the gun prevent movement between the barrel and the yoke. In guns designed for case ammunition, the yoke is replaced by a housing.



100 mm/55 Model 1968 intended to increase their firing rate.

CAQ - Contre-Avions Quadruple. French for "AA Quad Mounting."

Carriage - That part of the mounting which is carried in or upon the stand into which the trunnions seat. The carriage moves with the gun in train, but is fixed in elevation with the gun pivoting upon its trunnions for elevation changes.

CAS - Contre-Avions Simple. French for "AA Single Mounting."

Casemate - An armored enclosure containing a gun mounting. Unlike a turret, this enclosure does not rotate.

CP - Centre Pivot. British designation for a gun mounting that has a central axis for rotation on the horizontal axis. These mountings generally used a circular mounting plate bolted to the deck and supported by a below-deck, ring-shaped bulkhead known as the "gun support," which was used mainly for stowage. A lower roller path was machined on the base ring, with a similar upper roller path machined on the bottom of the turntable platform. Between the two machine paths were a ring of horizontal rollers which carried the weight of the mounting and gun. At the center of the turntable was a light cage which contained the vertical thrust rollers. This was the actual "center pivot" point. Electric cabling containing the fire control and illumination circuits ran through the center pivot. This cabling had enough slack to allow the mounting to train to its limit stops. In the USN, this type of mounting was called a "Pedestal" - see below.

Central Pivot - In the USN, this was a compact gun mounting with the center of rotation just below the gun barrel. Used a short "U" shaped bracket whose arms held the trunnions while the base of the "U" was mounted atop a small-diameter turntable.

Delay coil - When guns are mounted closely together in a turret, the shells may strike each other in flight or the individual airflow of one projectile may disrupt the adjacent projectiles, causing obvious problems. Starting in the 1920s, the USN alleviated this problem on their three-gun and triple mountings by installing a device which caused a brief delay, about 0.060 seconds, between when the outer guns fired and when the inner gun fired. Another method of reducing shell interference was used by the British in their "Town" and "Colony" six-inch (15.2 cm) cruisers of World War II, where the center gun of each triple turret was set back 30 inches (76.2 cm) from the outer two guns. This allowed all three guns to be fired simultaneously, at the cost of some complications in the design and construction of the gun house.

DCA - Défense Contre Avions. French for "Defense against aircraft" or anti-aircraft weapon.

Dopp MPL - Doppelt Mittel-Pivot-Lafette. German for "Twin central pivot mounting."

DrhL - Drehscheiben-Lafette. German for "turntable mounting." Generally used for turret mountings.

Drh Tr - Drehturm. Another German abbreviation for "Turret."

Elevation - The angle to which a gun can be moved on the vertical axis past the horizontal. For instance, a gun with a 90 degree elevation would be pointing straight up. A gun at 0 degree elevation would be pointing at the horizon. A gun with -10 degree elevation would be pointing below the horizon.

Gunhouse - The armored portion of the rotating structure extending above the barbette.

Gun Pit - A depression or opening on the gun deck into which the breech end of the weapon is lowered when the gun is raised to high elevations. This allows the trunnions of the gun to be mounted lower, thus lowering the overall height of the mounting while still allowing for high gun elevations.

Gun Port Shield - Curved armor plate attached to a gun barrel such that it seals the gun port in the glacis plate, regardless of the elevation of the gun. Gun ports are by their very nature weak points in the armor protection of a gun mounting or turret. Gun shields seal these openings and are intended to provide at least some measure of protection from shell splinters. In addition, many gun shields are designed so as to keep water and weather out of the interior of the mounting or turret. Some images of gun shields may be seen in these photographs of a USN 6"/47DP and a German 38 cm SK C/34.

Handling Room - Compartment just below the gun mounting where ammunition brought up from lower storage locations is loaded into hoists or scuttles for transferring up to the guns.

Kenyon Doors - British shell-handling device replacing shell bogies in some large-caliber mountings designs of the early 1900s. This was a tilting door which provided a flash-tight means of transferring shells between the shell room and the turret stalk, essentially similar to what the USN called a "scuttle" in their mountings. Named after the inventor, Thomas Kenyon. See this image of HIJMS Kongo from Vickers Photographic Archive for a photograph of a Kenyon Door as used on that ship.

Kst.Drh.L - Küsten-Drehscheiben-Lafette. German for "coastal turntable (turret) mounting."

Magazine
1) For smaller weapons, this is a metal or plastic box which contains multiple rounds. This is attached to the weapon and supplies rounds into the firing chamber.
2) Compartment on a ship where ammunition is stored.

MPL - Mittel-Pivot-Lafette. German for "central pivot mounting."

P - Pedestal. British designation for a compact gun mounting with the center of rotation just below the gun barrel. A short "U" shaped bracket held the trunnions with the base of the "U" mounted atop a small-diameter turntable. Similar in design to a Central Pivot mounting as used in the USN.

Passing Box - A small container mounted between compartments with a flap or door on each end and used to provide a flash-tight method of moving powder bags from one compartment to another. Usually there is a mechanical connection such that only one flap can be open at a time.

Pedestal - In the USN, this is a mounting where the entire gun carriage turns on a roller-race. The carriage is usually slab-sided with the sides running all the way down to a platform whose bottom forms the top of the roller race.

Pintle - A flexible mounting where the gun is mounted at the top of a vertical post or rod.

Powder Room - A compartment where propellant charges are stored.

Projectile or Shell Flat - Usually refers to that portion of a magazine directly adjacent to the rotating structure of a turret. May also be used to refer to that portion of the rotating structure onto which projectiles are moved from their storage locations in the magazines.

Recoil Cylinders and Counter-Recoil Cylinders - Recoil Cylinders absorb the forces generated when the gun is fired. These normally consist of a hydraulic system using a piston whose rod is surrounded by a spiral spring. The cylinders are normally secured to a stationary part of the mount while the piston rods are secured to the gun. When the gun fires, the piston moves through the cylinder and the recoil force is checked by the friction of the hydraulic fluid as it passes from one side of the piston to other side via apertures not filled by the piston, such as grooves in the wall of the cylinder. By varying the width of these grooves, the amount of friction generated as the piston moves can be increased or decreased as desired. During the recoil stroke, the spiral spring is compressed. This compression force is used to push the gun back into battery. As the piston returns to its starting point, the hydraulic fluid again moves through the apertures, aiding in controlling the counter-recoil stroke. The counter-recoil stroke can be violent and in larger guns counter-recoil cylinders are used to better control the speed of the return stroke. A counter-recoil cylinder is essentially a recoil cylinder designed so as to produce the most friction as the gun returns to battery.

RP - Remote Power. World War II British designation for gun mounts equipped with RPC. Usually followed by a number which represented the type of power control. The RP10 series were hydraulically operated while the RP50 series were electrically operated.

RPC - Remote Power Control. Also known as "Auto Control" in the USN. This is a subject in itself. In its barest essentials, this means that the gun director and associated components automatically control the laying of the guns without manual intervention by the gun crew.

WNUS_16-50_mk7_scuttle_pic.jpg
Scuttle - In the USN, a shell or powder handling device that allows a flash-tight transfer from one compartment to another, such as from a handling room up to a gunhouse. Commonly, this was a handle-operated rotating hollow drum with an opening on one side, with the opening accessible from only one compartment at a time. For example, a scuttle going between a handling room and a gunhouse would be loaded on the handling room side with a powder bag. Moving the handle rotated the opening in the drum over to the gunhouse on the other side, thus keeping the two compartments isolated from one another. At right is a picture of a scuttle used to transfer powder bags from a magazine onto a powder hoist on USS Iowa BB-61.

Sighting port - An opening for a gun-sight in the front of the gun-shield or turret glacis plate.

Sighting hood - Armored cover protecting the gun-sights protruding through the roof of a gunhouse or turret, although many of these were completely open to the front. On British capital ships of the World War I-era, superfiring turrets could not fire within 30 degrees of the axis because the blast effects would have penetrated into the lower turrets via the front openings in the sighting hoods. These hoods also represented a weak point in the protection of the turret and acted as shell traps. Several ships were damaged during World War I when German shells hit these ports, perhaps most notably on Q turret of HMS Tiger during the Battle of Jutland (Skagerrak) in 1915.

Shell Ring - On USN battleships and cruisers built in the 1930s-40s most of the projectiles were stored on fixed and rotating rings which were part of the upper and lower shell flats. Each storage flat was sub-divided into three concentric rings. The outer, or fixed ring, is attached to the stool and does not rotate. The center ring, or shell-handling platform, is part of the rotating structure including the gunhouse and contains the projectile hoists. It also mounts the parbuckling gear for moving the projectiles from their storage locations and onto the hoists. No projectiles are stored on this ring. The inner, or rotating ring, is a power driven platform resting on rollers which can be rotated in either direction and is supported by the rotating structure. The inner ring may be locked to the rotating structure (center ring) or to the stool as needed. Normally, the shells on this ring are the ones fed to the guns while those on the outer ring are moved only during non-firing periods.

Sleeving - In a multi-gun turret, if each individual gun can be raised independently of the other guns, then the guns are said to be individually sleeved. Guns that are not individually sleeved are said to share a "cradle" (UK usage) or a "slide" (USA usage). See "Turret Definitions," below.

Slide - The slide is that non-recoiling part of the mounting through which or upon which the gun or the gun slide cylinder moves in recoil and counter-recoil motions. The slide moves with the gun in train and elevation.

Stabilized mounting - A type of mounting which keeps the weapon at a constant point of aim regardless of the movement of the ship. May use as many as four different axes of motion; elevation, train, crosswise tilt (roll correction) and lateral tilt (pitch correction).

Stalk - That portion of the rotating structure of a turret that extends down into the ship.

Stand - That part of the mounting which is secured to the structure of the ship and in or upon which the carriage rests and is moved in train.

Stool - The fixed circular foundation bulkhead that supports the rotating elements of the gun house.

Superfiring - A gun mounted such that it can fire overtop another mounting without elevating its gun barrels from the horizontal is said to be superfiring. For example, on most ships with two forward turrets mounted on the centerline, the second turret from the bow is mounted higher than the first turret such that it may fire forward at almost any elevation. The second turret is thus superfiring.

Swashplate Engine - This was a type of steam-powered reciprocating engine employed by the British that used a circular plate (swashplate) in place of a crankshaft. These swashplate engines contained multiple pistons which were used to press down in sequence near the outer edge of the plate, making it wobble as it rotated about its center. Using a swashplate engine for turret training and elevation had the advantage of smoother incremental movements, as the jerking caused by the back and forth motion of the pistons was not directly coupled to the driveshaft.

Train - The angle to which a gun or turret can be rotated on the horizontal axis. For instance, a bow gun or turret pointing directly forward is said to be trained to 0 degrees. If it could rotate to point directly astern, then it would be trained to 180 degrees.

Transferable Mounting - A British term used in the early part of the twentieth century, meaning that the gun mounting was simply bolted to the deck with no other connections and so could be easily removed and used elsewhere. Replaced by "UD" (see below) in most official publications.

Turret - There is always a controversy about whether a particular rotating enclosed gun emplacement should be called a "Turret" or a "Mount." In the USN, the difference between a turret and a mount is that a "Turret" is built into the ship, has a stalk that extends well below the weather deck and includes a barbette, while a "Mount" is not part of the ship's structure and does not include a barbette. As a general rule, 5 inch (12.7 cm) and smaller guns are in "Mounts" while 6 inch (15.2 cm) and larger guns are in "Turrets." Other navies had similar distinctions.

Turret Definitions - In the USN, when multi-gun turrets are described as "two-gun" or "three-gun" it means that their guns are individually sleeved and that each gun can elevate independently of the others. When the mounting is described as "twin" or "triple" it means that all guns share a single slide or cradle and that individual guns can not elevate independently from the others. Other nations do not use these distinctions. On my weapon pages, the description for each weapon will indicate whether the mountings were individually sleeved or not.

UD - Upper Deck. British designation of the 1930s and 1940s referring to a gun-mounting that did not pierce the deck on which it was mounted. See "Transferable Mounting" and "BD," above.

VB and VCP - Vavasseur Barbette and Vavasseur Central Pivot Mountings. British gun mountings of the late 1800s that used inclined ramps to help absorb recoil forces. Named after Joseph Vavasseur (1834 - 1908) who at one point was connected with the Armstrong-Whitworth Co. and who is best remembered for inventing the process of using hydraulic pressure to fit copper driving bands onto projectiles in 1874.

Definitions and Information about Naval Guns - Part 1
 
Projectile Designations

AA - Anti-Aircraft.

AAC - Anti-Aircraft Common.

AAVT - Anti-Aircraft with Proximity Fuze.

AHEAD - Advanced Hit Efficiency And Destruction.

AP - Armor Piercing. Projectile for use against heavily armored targets. Very little explosive within the shell, as it must be almost solid in order to penetrate through armor plate. The USN has designated all capped armor piercing projectiles asAP since the early 1900s. See "APC" below.

APC or CAP - Armor Piercing Capped or (rarely used) Capped Armor Piercing. Most AP shells have a hard steel cap fitted over the nose which is intended to exert a high initial force on the face of the armor. In addition, a ballistic cap is usually fitted over the AP Cap to provide a more streamlined shape for better aerodynamic characteristics. See "Cap" below.

APDS - Armor Piercing Discarding Sabot.

APFSDS - Armor Piercing Fin-Stabilized Discarding Sabot.

API, AP-I, APT or AP-T - Armor Piercing Projectiles that include a Tracer (Incendiary).

AR - British designation meaning "Anti-Radar." See "Window" below.

BL&P or B.L.&P. - Blind Loaded & Plugged. Same as a Blind Shell. Used for training purposes or for target practice.

BL&T or B.L.&T. - Blind Loaded Shell with a Tracer. Used for training purposes or for target practice.

CCAMS - Course-Corrected Anti-Missile Shell.

Common - Common projectiles were originally shells - which literally means a hollow container - filled with black powder and used for attacking lightly armored or unarmored vessels. By the 1930s, this term was used by a few navies to describe any non-armor piercing shell. By that time, the bursters were less sensitive explosives, such as TNT. In the USN, Common projectiles of the 1920-1950 period did not have caps or hoods and were designed to penetrate approximately one-third of their caliber of armor. See "Special Common" below.

CLGP - Cannon-Launched, Guided Projectile. Long-range ballistic projectiles using terminal laser guidance developed during the 1970s for the USN's 5"/54 Mark 42 and 8"/55 Mark 71 guns.

CNF - Common, nose fuze. British projectile designation.

CP - Common Pointed. British designation for shells of poured or cast unhardened steel. Used a powder filling and were manufactured for 2-pdr. to 6 inch (15.2 cm) guns. Obsolete by World War II.

CPBC - Common Pointed Ballistic Cap. British designation for shells with ballistic caps of 6 inch (15.2 cm) and larger intended for use against medium thicknesses of armor. After 1946 this designation was changed to SAPBC - Semi-Armor Piercing Ballistic Cap.

CPC - Common Pointed Capped. British designation for capped shells of 6 inch (15.2 cm) and larger for use against lightly armored targets. Used a mild steel cap. Little armor penetration capability but large bursting charge. Obsolete by World War II.

DART - Driven Ammunition Reduced Time of flight. Sub-caliber guided projectile with canard control, intended to improve the performance of the OTO-Melara 76/62 gun in the antimissile role. Uses a radio-frequency beam rider guidance system which utilizes the firing ship's tracking radar.

ERGM - Extended Range Guided Munition. Effectively missiles fired from a gun barrel, these special projectiles are currently under development for the US Navy for the 5"/62 Mark 45 Mod 4 and 155 mm AGS gun systems.

FAP - Frangible Armor Piercing. FAP is usually a projectile with a tungsten alloy core which breaks up into multiple fragments when it strikes a hard surface. The FAP projectile combines armor penetration, blast effects and incendiary action, all from an inert projectile that has no more logistical safety problems than a training round.

FAPDS - Fragmented Armor Piercing Discarding Sabot.

HC - High Capacity. A USN designation for projectiles intended for use against lightly armored targets. Contains a relatively large amount of explosive as compared to an armor piercing or common projectile. Burster was between 7.0% to 12.6% of total projectile weight.

HE - High Explosive or High Effect. Same as HC.

HEI or HE-I - HE projectiles that include an Incendiary.

HE-I-SD - Self-destructing incendiary HE projectile.

HE-CVT - HE with a Controlled Variable Time (proximity) fuze.

HE-IR - HE with an infrared fuze. These rounds use a passive IR fuze that operates only on the infrared spectrum detected in the exhaust gasses of jet and hot missile targets. These fuzes are harder to jam than radar-type proximity fuzes.

HE-MOM - HE Multirole OTO Munitions. OTO-Melara ammunition with proximity fuzing and tungsten cubes surrounding the bursting charge.

HE-PF-OM - HE Pre-Fragmented OTO Munition.

HE-PD - HE with a Point Detonating (contact) fuze.

HE/SD - Self-destructing HE projectile.

HENT - British HE shell with TNT burster.

HET or HE-T - HE shell with a tracer.

HE-T/SD - Self-destructing HE-T shell.

HETF - British high explosive projectile with time fuze.

HE-VT - High Explosive with a Variable Time (proximity) fuze.

ILLUM or Illuminating - Commonly called "Star Shells," these projectiles are usually filled with magnesium and are used at night to light up (illuminate) the target. Many use a parachute in order to slow their descent.

ILLUM-MT - Illumination round with a Mechanical Time fuze.

LRBA - Long Range Bombardment Ammunition. USN munition developed as part of the "Gunfighter" program of the late 1960s. These were unguided 5" (12.7 cm) projectiles enclosed in a sabot and fired from 8" (20.3 cm) gun barrels. These sub-caliber projectiles had a maximum range of about 72,000 yards (66,000 m) and were successfully used against Viet Cong targets at 70,000 yards (64,000 m).

LRLAP - Long Range Land Attack Projectiles. These are being developed as part of the AGS program.

MPDS - Missile Piercing Discarding Sabot.

OEA - Obus Explosif en Acier. French designation for High Explosive projectiles.

OEcl - Obus Eclairant. French designation for Starshell.

OI - Obus Incendiare. French designation for Incendiary shell.

OPf or OPF RC - Obus de Perforation or Obus de Perforation de Rupture Coiffé. French designation for APC.

OPfK - Obus de Perforation dispositif 'K'. French designation for APC with dye bag. Unlike many nations, French APC dye shells included a nose fuze and a small explosive charge to disperse the dye. This made it possible to not only color the shell splashes but also to color hits.

PFHE - Proximity Fuzed High Explosive.

RAP - Rocket-Assisted Projectile.

SAP - Semi-Armor Piercing. Projectiles supplied for smaller guns for use against moderately armored targets.

SAPBC - Semi-Armor Piercing Ballistic Cap. British projectile designation. See "CPBC" above.

SAPER - Semi-Armor Piercing Extended Range.

SAPHEI-T - Semi-Armor Piercing High Explosive Incendiary Tracer.

SAPOM - Semi-Armor Piercing OTO Munition.

SAPOM-ER - Semi-Armor Piercing OTO Munition Extended Range.

Special Common or SP Common - USN unofficial designation of the 1920-1950 period for those Common projectiles that used both windshields and hoods. These projectiles were designed be able to penetrate approximately one-third to one-half their caliber of armor. They differed from AP projectiles by not having a cap and in having a larger burster cavity. Burster was 2.1% to 3.99% of total shell weight.

Shrapnel Shell or SS - British designation. A thin-walled shell body with a powder filled central tube surrounded by lead antimony balls embedded in resin. Used a time fuze. Obsolete by World War II.

Window or Window Load - Projectiles containing metal foil strips, which, when scattered high in the air by a small burster charge, serve to jam radar sets by creating a multitude of images.

WP - White Phosphorous or "Wiley Pete." Projectiles used to create a small smoke screens, which is why they are also known as "Smoke" rounds.

Fuzes

A fuze is a device that initiates the detonation of the projectile burster. Fuzes may be divided into two general categories, contact and non-contact. Examples of contact fuzes would be super quick and delay while examples of non-contact fuzes would be time and proximity. An overview of fuzes and fuze terminology used since the 1900s follows:

  • ADF or Auxiliary Detonating Fuze - Many USN nose fuzes have an "auxiliary detonating fuze" between them and the burster. These auxiliary fuzes provide the heavier shock which actually detonates the bursting charge. Auxiliary fuzes also act as a safety feature by preventing the projectiles from exploding should the primary fuze be accidentally actuated prior to the arming of the auxiliary detonating fuze.
  • Boresafe Fuze - Type of fuze having an interrupter in the explosive train that prevents the fuze from functioning until after the projectile has cleared the muzzle of the weapon. A "non-boresafe fuze" does not have this feature.
  • Base Fuze - Fuze located at the bottom end or base of the shell. This is the most common location for AP and SAP projectiles as it avoids weakening the nose of the shell and protects the fuze from damage as the projectile passes through armor. Some HE/HC shells have both nose and base fuzes as this increases the probability of the shell detonating under differing conditions.
  • CCF - Course Correcting Fuze. A smart fuze that uses aerodynamic fins together with the Global Positioning System (GPS) in order to steer an otherwise ordinary ballistic projectile.
  • Contact, Impact or Percussion Fuze - A fuze initiated only after the projectile strikes the target. There are two general types of contact fuzes: "Delay" and "Super Quick" both further defined below.
  • Combination Fuze - A fuze that incorporates both Contact and Time functions. The fuze may function either when it strikes the target or after the set time expires.
  • Delay Fuze - A contact fuze that detonates the projectile only after it has impacted and penetrated some distance into the target. A "short delay" means that the fuze initiates detonation within a few thousandths (0.00X) of a second after impact. For naval guns, short delays are generally used for HE/HC rounds while longer delays are used for AP rounds. Some delay fuzes have a ring or dial which allows adjustment of the delay time. For AP projectiles, it is desirable to have the shell detonate only after it has penetrated past the armor plating, thus letting it get into the "vitals" of the target ship's interior. For most AP rounds of the twentieth century, this delay was usually about 0.030 to 0.070 seconds, roughly equivalent to 35 to 80 feet (10 to 30 m) of travel. In addition, some thickness of armor plate was needed to initiate the fuze action. For example, the USN required that for hits of 0 degrees obliquity that the AP fuze would not activate unless the armor plate was at least 1 inch (2.54 cm) thick.
  • Nose Fuze - Fuze is located at the top point of the shell. This is the most common location for HC and HE shells as the fuzes can be set to allow little or no time delay and thus detonate the bursting charge immediately upon impact.
  • Proximity Fuze - Fuze containing a simple radar that can detect the nearness (proximity) of a target. Also called "influence fuze." First used in World War II on USN 5 in (12.7 cm) AA shells which were called "VT Fuzed" where VTstood for "Variable Time" (it appears to be a myth that "VT" was a reference to "Section T," the BuOrd development team for proximity fuzes. See the Technical Board Essay on VT Fuze naming). These fuzes are also widely used for anti-personnel rounds for land artillery as they eliminate the need to accurately set a time fuze to explode the projectile at a fixed distance above the target. During World War II, the US Army called these posit or pozit fuzes which meant that the proximity fuze allowed the shell to detonate at the most effective height or "position" above the ground. Since World War II, proximity fuzes small enough to fit onto 40 mm AA rounds have been developed. The modern British versions of proximity fuzes are called TTB - Target Triggered Burst. CVT or "Controlled Variable Time" fuzes have a mechanical timer which activates the radar when it is close to the target. This helps to prevent premature detonations due to heavy rain or other non-target influences.
  • Super Quick Fuze or Instantaneous Fuze - A contact fuze designed to detonate the projectile before it has penetrated any distance into the target. Super quick fuzes are commonly used on anti-aircraft rounds that are intended to shred the outer airframe.
  • Time Fuze - Fuze has an adjustable mechanism - usually an incremented dial or "ring" or, in more modern fuzes, an electronic timer - which is used to set a delay time. Commonly used for AA, smoke and illumination projectiles, this type of fuze is used to set the time between when the shell is fired and when it detonates.

Propellants

An overview of some of the more common propellants used by naval guns since the 1880s.

  • Single-Base, Double-Base, Triple-base and Composite Base Propellants - Propellants are normally classified into three types; single-base, double-base and composite. Single base propellants are primarily gelatinized nitrocellulose that do not contain an additional explosive ingredient such as nitroglycerin. Double-base propellants are mainly compositions that are predominately nitrocellulose and nitroglycerin. Triple-base propellants are double-base propellants to which has been added a third explosive, Nitroguanidine (see below). Composite propellants are compositions that contain mixtures of fuel and inorganic oxidants but do not contain a significant amount of nitrocellulose or nitroglycerin. There are also combinations of composite and double-base propellants.
  • Ballistite - This is a double-base propellant for rockets. It is composed of nitrocellulose and nitroglycerin, blended together with diphenylamine, which acts as a stabilizer. This mixture burns with a considerable amount of flash and smoke, and generates a great volume of gas. Ballistite burns progressively, but at a rate dependent upon the composition and physical characteristics of the propellant grain, the temperature of the propellant prior to ignition and the gas pressure obtained during combustion.
  • Black Powder - Commonly known as "gunpowder," this was obsolete as a propellant by the 1880s and rarely used after 1900 by the major powers. It did continue to be used for igniter patches on bag ammunition. Black powder is a mixture of potassium nitrate or sodium nitrate, charcoal and sulfur. It is hydroscopic and subject to rapid deterioration when exposed to moisture. It is also one of the most dangerous explosives to handle because of the ease with which it is ignited by heat, friction or spark. Black powder as a gun propellant has several disadvantages: (1) it leaves a large amount of residue, (2) it produces large quantities of smoke, (3) it causes rapid erosion of the gun bore and (4) its velocity of reaction is too rapid, giving an abrupt hammer blow to the projectile and then rapidly decreasing energy. This last reason is why gunpowder guns had short barrel lengths. Muzzle velocity was generally less than 1,600 fps (488 mps).
  • Brown Powder or Cocoa Powder or Slow Burning Cocoa - Invented in Germany in the late 19th century, this was gunpowder that was made by using an underburned straw charcoal that gave it the characteristic color from which it took its name. This charcoal gave a denser and hence slower burning structure to the powder and thus permitted better regulation of pressure. Brown powder is similar to black powder (gunpowder), each being a mixture of potassium nitrate, charcoal and sulfur, but brown powder has a lower sulfur content (3% versus 12%) and a correspondingly higher potassium nitrate content. The reduced sulfur content results in a slower rate of deflagration (burning) and the higher potassium nitrate content supports a more complete burning of the charcoal and thus releases more energy. The slower burning nature of brown powder allowed longer barrel lengths and thus higher muzzle velocities, with the maximum being about 2,200 fps (671 mps). However, this propellant is notorious for producing vast quantities of smoke as only about 35 percent of its weight is actually converted into propellant gas.
  • Cordite - A double-base smokeless powder composed of nitroglycerin, guncotton and a petroleum substance, usually gelatinized by the addition of acetone, and the mixture then pressed into cords which resemble brown twine.
  • Flashless Powder - Propellant formulation that reduces the amount of flame emitted from the gun muzzle. Useful in night engagements not only because it does not give away the position of the firing ship, but, more importantly, it does not blind the gunners and optical fire control operators. Not really "flashless" but much less so than standard propellants. Flashless propellants normally produce significantly more smoke than do smokless propellants, and there is always the need to strike a balance between the two effects.
  • Gun Cotton or Nitrocellulose - Explosive substance formed by the nitration of cotton or some other form of cellulose. As a projectile force, gun cotton has around six times the gas generation of an equal volume of black powder and produces less smoke and less barrel heating. Guncotton releases about 1,100 kilocalories (Kcal) of energy per kilogram, nearly twice that of black powder, almost the same as TNT and two-thirds that of nitroglycerine. Moist or "wet" guncotton is relatively stable but can be easily exploded by using a small amount of dry guncotton (which is sensitive to shock) to start the deflagration. Some history about guncotton: In 1838 the French chemist Theophile Jule Pelouze discovered that an explosive could be produced by nitrating cotton, that is, by treating cotton with nitric acid in such a way as to cause NO2 groups from the nitric acid, HNO3, to enter into combination with the cotton cellulose. He thus produced cellulose nitrates, generally called nitrocellulose. His explosive was the first guncotton, but it was an inconsistent mixture and was not put to practical use. The German-Swiss chemist Christian Friedrich Schönbein discovered in 1845-46 that by nitrating cotton with a mixture of nitric and sulfuric acids, an explosive of good quality would result and that the nitration process could be satisfactorily controlled. Manufacture of guncotton via his process was undertaken in several European countries, but poor quality control led to a series of disastrous explosions in many of the factories where it was being produced. The researches of various investigators during the middle of 19th century, notably those of General von Lenk in Austria and the British chemist Frederick Abel at Woolwich Arsenal (who, together with James Dewar, later invented cordite), showed that the danger was due to the presence of impurities, which could be removed by careful courses of treatment. The methods of purification which they introduced consisted principally in washing and boiling, together with pulping the material to facilitate cleansing. In 1865, Abel was the first to safely produce good quality guncotton.
  • Nitroguanidine (NQ) - Needle-shaped solid used in explosives and triple-base smokeless powders. Nitroguanidine is an insensitive, non-flammable explosive used to reduce flash in propellants. NQ lowers the temperature of the flame and increases gas volume. This combination reduces flash and gas temperatures which reduces bore erosion and thus increases barrel life.
  • Smokeless Propellant - Propellant formulation that reduces the amount of smoke emitted from the gun muzzle. Not really "smokeless" but much less so than black powder (gunpowder) or brown powder. Smokeless propellant was invented by the French chemist Paul Vielle in 1883 and involved the "gelatinization" of nitrocellulose. Gelantinization consists in transforming fibrous nitrocellulose into a dense, non-porous material that looks like celluloid and can be given a definite shape. As invented by Vielle, this involved dissolving nitrocellulose by the use of a solvent mixture, such as alcohol and ether. As the solvent evaporates, what is left behind is a gel - hence the name "gelantinization" to describe the process. This gel produces a single-base energetic material that can be worked into different forms. This is sometimes known as "Solvent Propellant" to distinguish it from "Solventless Propellants."
  • Solventless Propellants - These propellants use a plasticizer, usually nitroglycerine, which is worked into the nitrocellulose fibers under the mechanical effect of a roll mill and the use of heat to produce a gel. Following this mixing process, the gel is then pushed through an extrusion press to form the propellant grains. These operations are known as "rolling and drawing."

Propellants by Country

Abbreviations of the more well-known propellants used by the major naval powers. Additonal information on most of these propellants may be found further below.

Britain

  • EXE - Extra Experimental
  • Mark I - The original cordite formulation adopted by the Royal Navy in 1889
  • MD - Modified Cordite, adopted by the RN in 1901
  • MC - Modified Cracked, adopted by the RN in 1917
  • SC - Solventless Cordite, also known as Solventless Carbamite, adopted by the RN in 1927
  • HSC - Hot Solventless Carbamite
  • HSCT - Hot Solventless Carbamite Tubular
  • NF, originally known as NFQ - Triple-base flashless propellant, adopted by the RN during World War II
  • NQFP - Reduced flash composite of NFQ and SC
  • PBr or P.Br. - Prismatic Brown
  • PBl or P.Bl. - Prismatic Black
  • RLG - Rifle Large Grain
  • SBC - Slow Burning Cocoa
  • SP - Small Pebble
France
  • Poudre B - Poudre Blanche or "white powder." The original French nitrocellulose, adopted by the French Navy around 1890. The name was to distinguish the new propellant from gunpowder, which was known as Poudre N for Poudre Noire (black powder)
  • BM - Blanche Modifié? or "Modified White?" Improved French nitrocellulose adopted about 1912.
  • SD - Solventless double-based propellant adopted in the 1930s
Germany
  • RP - Rohr-Pulver or "Tube powder." Usually known by their model year, such as RP C/38 meaning a propellant adopted in 1938.
Italy
  • C - Italian cordite, adopted about 1900
  • NAC - Solventless propellant in use after 1936
  • FC4 - Solventless propellant in use after 1936
Japan
  • C - Japanese cordite, equivalent to British MD and adopted by the Imperial Navy in 1907
  • C2 - Type 2 Cordite, adopted in 1912. Later formulations were sequentially designated, such as C3
  • T2 - Type 2 Cordite in tubular form. Later formulations were sequentially designated, such as T3
  • DC - Deutsche Cordite, adopted in 1924. Later formulations were sequentially designated, such as DC3
  • DT - Deutsche Cordite in tubular form
  • FD - Flashless Deutsche Cordite
United States of America
The designations below are normally followed by a number that indicates the sequence of manufacture. The combination of the letters and the number is termed the index or the lot of the powder.

  • SP - Smokeless Powder, the original single-based propellant adopted by the USN in 1900
  • SPR - Smokeless Powder with Rosaniline dye, in service with the USN for a brief period between 1905 and 1908
  • SPD - Smokeless Powder with Diphenylamine as a stabilizer, adopted by the USN in 1908
  • SPDB - A blend of diphenylamine stabilized powders of different lots. The purpose of blending is to provide a uniform index of ample size and desired characteristics from smaller remnant lots.
  • SPDF - A flashless formulation of SPD
  • SPDN - SPD with nonvolatile materials added to reduce its hydroscopic tendencies. The N stands for nonhygroscopic.
  • SPDW - Reworked propellant intended for target use. Propellant is ground down, reprocessed and then made into new grains.
  • SPWF - Reworked propellant to which a flashless element has been added
  • SPDX - Water-dried SPD
  • SPC - Smokeless Powder with Carbamite (ethyl centrality) added for stability
  • SPCF - A flashless formulation of SPC
  • SPCG - Flashless triple-based propellant stabilized with carbamite. The G is short for NG, the designation forNitroguanidine.

See the essay Naval Propellants - A Brief Overview on the Technical Board for more information.

Ammunition, Fuzes, Projectiles and Propellants Definitions

Amatol - An explosive mixture of ammonium nitrate and TNT.

Arrow Shell - A fin-stabilized HE projectile. In German, "Pfeilgeschoss."

Bag Ammunition - Ammunition in which fabric bags are used to hold the propellant and the projectile is handled separately. Propellant bags were primarily manufactured from a raw silk also known as "cartridge cloth" or else from a special coarse wool twilled on both sides known as "shalloon." Unlike cotton, these materials burn without leaving any smoldering residue in the barrel which would present a safety hazard when loading the subsequent round. Shalloon was used by most nations as it was relatively inexpensive but silk was preferred in the USN as it reduced barrel wear. Bags made from Rayon rather than silk were used in the USN for some guns after a serious propellant fire aboard USS South Dakota BB-57 in 1945 was traced to a spark generated when a silk bag was removed from its metallic container.

no21987-German_38cm_apc.jpg
Ballistic Cap - Often called a "windshield," this is a covering on the nose of a projectile which is intended to provide a more streamlined shape for better aerodynamic - ballistic - characteristics.

Ballistic Coefficient - Measure of the ability of a projectile to overcome air resistance. Ballistic coefficient (BC) = SD / F, where SD is the sectional density of the projectile and F is a form factor for the shape of the projectile. Sectional density is calculated from the mass (M) of the projectile divided by the square of its diameter. The value of F decreases with as the pointedness of the projectile increases. A projectile shaped like a sphere would have the highest F value while one in the shape of a long needle would have the lowest F value.

Ballistic Conditions - Conditions which affect the motion of a projectile in the bore and through the atmosphere, including muzzle velocity, weight of projectile, size and shape of projectile, rotation of the earth, density of the air, elasticity of the air and the wind.

Ballistic Curve - Actual path or trajectory of a projectile.

Ballistic Density - Computed constant air density that would have the same total effect on a projectile during its flight as the varying densities actually encountered.

Ballistic Efficiency - Ability of a projectile to overcome the resistance of the air. Ballistic efficiency depends chiefly on the weight, diameter and shape of the projectile.

Ballistic Length or Head Length - The length of the projectile's nose. See "crh" below.

Ballistic Limit - Velocity at which a given type of projectile will perforate a given thickness and type of armor plate at a specified obliquity. Also see "Armor Penetration Definitions," in Miscellaneous Definitions.

Ballistics, Internal, Intermediate, External and Terminal - Internal Ballistics is the study of what the projectile does from the moment of firing up until it leaves the muzzle of the weapon. Intermediate Ballistics is the study of the projectile between the time it exits the muzzle until it overtakes the muzzle shock waves and enters normal atmosphere. External Ballistics is the study of what the projectile does as it travels from the end of the intermediate stage to the target. Terminal Ballistics is the study of what the projectile does as it strikes the target.

Balloting - The bounding from side to side of a projectile in the bore of a gun.

Base - The after end of the projectile, usually described as that portion between the driving bands and the bottom of the projectile.

Base Bleed - This is a unit on the base of a projectile that generates a gas, something like a tracer. What this does is fill in the vacuum that is created behind a rapidly moving projectile and thus greatly reduces the amount of drag acting on the projectile. The gas also acts like a long tail, making the projectile more stable in flight. The end result of these actions is an increase in range and accuracy.

Base Cover - A metal cover that is crimped, caulked or welded to the base of a projectile. This cover prevents the propellant gasses from coming in contact with the explosive filler of the projectile through possible flaws in the metal of the base.

Base Plug - A removable seal in the base of a shell which holds in the explosive filler.

Belt, Ammunition - Multiple rounds of ammunition that are held together by a strip of fabric or metal. Used most often for feeding ammunition to automatic weapons. Ammunition belts may be disintegrating (linked), non-disintegrating or continuous loop.

Blind Shell - A shell containing no explosives or one having its fuzing disabled so that it should not explode. Often used for proof tests against armor plate.

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Boat Tailing - Tapering that part of the projectile behind the driving band to reduce air resistance, especially at low velocities. This type of design gives a projectile greater range but tends to increase wear on the gun barrel. It was long thought that boat tailing caused greater dispersion in the impact pattern, but a study published in 1978 by the US Army's Ballistic Research Lab showed that the opposite was true.

Body - The cylindrical portion of the projectile between the bourrelet and the driving bands. It is machined to a smaller diameter than the bourrelet to reduce the projectile surface in contact with the lands of the bore. The body contains most of the projectile filler.

Booster - An explosive of special character, usually of high strength and high detonating velocity, generally used in small quantities to improve the performance of another explosive, the latter constituting the major portion of the charge and made up of a less sensitive explosive. Also see "Gaine."

Bourrelet - Finely machined band or ring of metal just behind the ogive of a projectile, designed to support the front portion of the projectile by riding the lands as the projectile travels through the bore of a gun. Only the bourrelet and the driving bands of a projectile actually touch the rifling. Some projectiles have additional bourrelets located near the base of the projectile. On USN large caliber AP projectiles of the World War II period, rear bourrelets were located just before and after the rotating bands. These additional bourrelets act to reduce the tip-off angle by keeping the projectile body centered in the gun barrel after the forward bourrelet has exited the muzzle.

Brisance and Brisant - Brisance is the measure of how rapidly an explosive develops its maximum pressure. A brisant explosive is one in which the maximum pressure is attained so rapidly that the effect is to shatter any material in contact with it and all surrounding material.

Bursting Charge - The explosive charge within a shell. Known simply as "Burster." Some of the more well-known:

  • Black Powder or Gunpowder - Used as the burster in most shells prior to the early years of the twentieth century. A common procedure was to fill the shell cavity with gunpowder or to put the explosive into a loosely-restrained bag at the base of the projectile. In this latter variation, when the projectile struck the target it was intended that the bag would be torn loose from its restraints and flung forward against the interior of the shell. In either variation, these projectiles relied upon impact shock to set off the burster. About as reliable as it sounds, hence the intensive search for better explosives, more reliable fuzing and the interest in the Zalinsky "Dynamite Gun" experiments.
  • Composition A - USN burster made from a mixture of 91% RDX and 9% wax. In use near the end of World War II in a few AA projectiles.
  • Composition Exploding or CE - See "Tetryl" below.
  • Gun Cotton - See "Propellants" below.
  • Explosive D - USN burster made from "Dunnite" which is Ammonium Picrate, a salt formed from picric acid. Named after its inventor, Lieut.-Col. B. W. Dunn (1860–1936) US Army. Adopted by the US Navy in 1911, this explosive is very insensitive to shock, giving it a high margin of safety. This burster was used for almost all USN projectiles until long after World War II.
  • Pentolite - A mixture of TNT and PETN, usually 50/50. This was not as stable as TNT in storage. Used in some USN20 mm ammunition during World War II.
  • Picric Acid - A trinitrated derivative of phenol or trinitrophenol. Invented by the German chemist Hermann Sprengel and patented in 1885 by the French chemist Eugène Turpin in pressed and cast form for use in blasting charges and artillery shells. Picric acid is a powerful explosive but its strong acidity causes it to combine with iron in projectiles.
    • Ecrasite - Austria-Hungary picric acid.
    • Emmensite - USN picric acid.
    • Eversite - Italian picric acid.
    • Lyddite - British picric acid, trinitrophenol. Prior to 1908, the British used gunpowder as the burster for both AP and Common shells, but after that date Lyddite came into use for HE projectiles. In 1909, the Royal Navy began experimenting with APC using Lyddite as the burster and began introducing them into service the following year, even though testing had shown that this filling was more sensitive to shock than gunpowder and thus prone to explode prematurely before the shell had a chance to penetrate almost any thickness of armor plate.
    • Melinite - French picric acid.
    • Picrine - German picric acid.
    • Shimose - Japanese picric acid. Named after its inventor, Shimose Masachika (also spelled as Shimose Masakazu), but there is some evidence that it was actually based upon a sample of Melinite brought back from France. Adopted on 17 February 1893. Also known as PA bakuyaku (picric acid explosive).
  • Shellite - British burster adopted just after the end of World War I, this was a less sensitive picric acid mixture, containing a mixture of 70% Lyddite and 30% of the much weaker, insensitive explosive dinitrophenol.
  • Tetryl - Trinitrophenylmethylnitramine. A sensitive, high power burster. Tetryl is a light yellow crystalline material and was first made in 1877. Known in the British Royal Navy as Composition Exploding or CE.
  • TNA - Japanese tri-nitro-aniso, designated as Type 91 bakuyaku (Model 1931 Explosive). Adopted on 25 July 1931, this was a methylated derivative of picric acid and a more stable burster than Shimose.
  • TNT - Tri-nitro-toulene. Few, if any, nations used pure TNT. Instead, this was usually mixed with a desensitizer, such as beeswax. For example, German shells of World War II used a beeswax mixture with the concentration of beeswax decreasing from the head to the base of the cavity.
Bursting Charge Power - The following approximations of explosive power may be used using TNT = 1.00 as a reference point.
  • Before and during World War I
    • Black powder = 0.33 to 0.50
    • Guncotton = 0.50
    • Picric Acid = about 1.05 to 1.10
    • USA Explosive D = 0.95
  • After World War I
    • German and Italian TNT = 1.00
    • British Shellite = 0.96
    • Japanese TNA = 1.05
    • USA Explosive D = 0.95
  • Other Explosives (torpedo warheads, mines, depth charges)
    • Amatol (80/20) = 1.24
    • DD (Dinitronaphthalene/Dinitrophenol 60/40) = 0.82
    • PETN = 2.21
    • MDN (Melinite/Dinitronaphthalene 80/20) = 0.88
    • RDX = 1.94
    • Tetryl = 1.39
    • Torpex (TPX) = 1.50
    • HBX-1 = 1.17
    • HBX-3 = 1.14
    • German SW types = about 1.07
    • Japanese Type 97 (TNT/hexanitrodiphenylamine 60/40) = about 1.07
Two rules of thumb about Burster Power
1) The effect of the burster may be taken as being proportional to the square root of the weight of the bursting charge.
2) For the same basic shell design, the size of the bursting charge is proportional to the cube of the bore size.
Cap - Hardened steel nose piece of an APC projectile. Introduced by Russia and America in 1894 and adopted by the British Royal Navy in 1903. See illustrations on this page. The cap serves the following purposes:
1) It is shaped so as to increase the biting angle; that is, the angle at which the projectile will penetrate rather than ricocheting.
2) It spreads the shock of impact over the periphery of the nose instead of allowing the initial contact to batter the nose tip.
3) It pre-stresses the armor plate upon impact before the cap shatters away. This means that the shell body sees a weakened plate.

Cannelure - Means a ring-like groove or a groove encircling a cylinder. These have the following uses in ammunition and weapons:
1) On projectiles used in fixed ammunition: The groove provides a means of securely crimping the cartridge case to the projectile.
2) On armor-piercing bullets: The groove is used to lock the jacket of an armor-piercing bullet to the core.
3) In the rotating band of a projectile: The groove lessens the resistance from the rifling as the projectile travels down the gun barrel.
4) Around the base of a cartridge case: The groove is where the extractor takes hold to eject the spent case.
5) In the construction of British large-caliber, wire-wound weapons: Cannelured rings were used to prevent "steel choke" problems.

Cartridge - For rifles and pistols, this is usually defined as being the term for a complete round of ammunition, including the projectile, cartridge case, propellant and primer. For larger caliber naval weapons, especially those using separate ammunition, this term is usually applied to only the metallic propellant container, although the British also used this term to describe the individual fabric-wrapped charges used for bag guns. See next definition.

Cartridge Case, Powder Case, Propellant Case or Casing - A metallic container for holding powder charges and usually includes a primer element. This type of propellant container allows higher rates of fire and is less likely to catch fire in case of damage from a shell hit. It is also less likely to suffer a flareback type of disaster caused by the smoldering remnants from the previous powder charge. However, for larger caliber guns, it does require more complicated and heavier handling equipment than does bag ammunition. Germany used a variation of this for their larger guns, where the propellant was divided in to two sections, a fore charge in a bag and a main charge in a cartridge case. Also see "Fixed" and "Semi-Fixed."

Cartridge Case Size - Cartridge cases are usually designated by the diameter of the projectile they fire and by the overall length of the casing. Letter suffixes indicate the type of casing. For example, the famous Oerlikon 20 mm of World War II used 20 x 110RB casings. This meant that the cartridge cases were for 20 mm projectiles, had an overall length of 110 mm and had a Rebated Rim. It should be realized that this is an imprecise method of identifying casings, as it neglects body diameter and shape. Most cartridge cases are of one of the following types:

  • Belted - Cartridge cases having a belt of metal above the extraction groove approximately the same diameter as the rim. Denoted by the suffix B after the diameter and length values.
  • Rimless - Cartridge cases having an extraction groove with the base of the cartridge case being no wider than the rest of the cartridge case body. This type of cartridge case does not have a suffix following the diameter and length values.
  • Rimmed - Cartridge cases having a rim at the base wider than the rest of the cartridge case and not having an extraction groove. Denoted by the suffix R.
  • Semi-Rimmed - Cartridge cases that have a rim that is wider than the body of the casing with an extraction groove just above the rim. Denoted by the suffix SR.
  • Rebated Rim - Cartridge cases whose bottom rim is smaller in diameter than the body of the cartridge case. There is an extraction groove between the rim and the rest of the cartridge case body. Denoted by the suffix RB.
Cartridge Case, Bottle-Necked - A cartridge case whose main body diameter is significantly larger than that of the projectile and has a short "neck" section which holds the projectile. This design may be used with any of the above cartridge case types. A bottle-neck cartridge case holds more propellant for a given length than will a non-bottle neck cartridge case.
Cartridge Case, Tapered - A cartridge case whose body diameter increases from the neck to the rim. This type of cartridge case ejects easier from the firing chamber than does a "straight" walled cartridge case, as any backwards motion releases the entire cartridge case body from the walls of the firing chamber. Most military ammunition manufactured today has at least some degree of taper.

Case Ammunition - Ammunition using a cartridge case to hold the propellant. See "Fixed" and "Semi-Fixed" below.

Case Plug or Mouth Plug - The sealing device in the mouth of a cartridge case used for separate (semi-fixed) ammunition. This may be of cork, plastic or cardboard. The USN originally used a brass mouth cup to seal cartridge cases, but after one "boomeranged" back on board the transport SS Mongolia and killed two nurses in May 1917, cardboard ones were substituted.

Charge or Powder Charge - The amount of propellant used in firing a weapon.

Gun_Data_crh_pic.jpg
crh - Caliber Radius Head. The pointed head of a projectile is described in terms of its ballistic length and the radius of the curvature of its nose. Larger numbers mean a more streamlined profile. Properly, crh is shown as a dual number such as 3/4crh, with the first number indicating the ballistic length and the second number indicating the radius of the curvature, but it is often abbreviated to a single number such as 4crh. In the sketch at the right, the dotted line between Points A and B is the "shoulder" which is the start point of the nose and the distance between these points is the caliber of the projectile. In this sketch, the radius of the curvature is from Point A to Point E and is four times the caliber of the projectile. The vertical distance between Points C and D is the ballistic length and is the most important factor in the design of a shell for stability in flight. In this sketch, the ballistic length is 4, as Point E is on the same plane as Points A and B. From these numbers, this projectile would properly be described as 4/4crh but this would normally be abbreviated to just 4crh. Shells of this general shape are described as being "ogival headed" and have superior ballistic performance. As can easily be imagined, a 6crh shell is more pointed and streamlined than is a 4crh shell. When crh is described as 5/10crh it means that the radius is 10 calibers long but the ballistic length is that of a 5crh shell. When a projectile is described as 5/
Gun_Data_Infinity.jpg
crh it means that it has a ballistic length of 5 and its nose shape is conical (infinite radius), not ogival. Most USN projectiles had secant ogive ballistic nose shapes which were somewhat more conical than a simple tangent ogive (smooth merging joint with cylindrical lower-body side) and gave them a distinct "shoulder" where the nose met the cylindrical side of the lower body). This shape has slightly reduced air friction compared to a tangent ogive nose of the same length above the cylindrical body. For further information, see the essay Calculating crh on the Technical Board.

Clarkson's Case - British propellant charge container. These were flashproof containers for bag charges (cartridges). Charges were placed into these containers before they left the magazines. The Clarkson's Cases then rode up the hoists to the guns where the charges were removed only when it was time to load them into the breech. The Clarkson's Cases were reusable and were returned to the magazines for reloading.

Clearing Charge - A small propellant container that is used to remove a projectile "through the muzzle" following a misfire or when a projectile fails to seat properly and prevents closure of the breech. For semi-fixed (separate) rounds, the propellant case may be easily removed from the breech following a misfire or failure to seat, but there is no easy way to extract the projectile after it has been rammed. A clearing charge casing, being shorter than a standard full-charge casing, is then used to remove the projectile. The clearing charge also gives the projectile a softer blow than does a standard charge and thus provides a margin of safety.

CSP2 - Chilworth Special Powder No. 2. A dual-base propellant made by the Chilworth Gunpowder Company prior to World War I and used by Elswick for many of their export guns.

Dark Tracer and Dark Ignition Tracer - Dark Tracer was non-luminous while Dark Ignition tracers did not ignite until the projectile was 100 to 400 yards (90 to 370 m) from the muzzle. The USN developed these tracers late during World War II for their 20 mm and 40 mm automatic weapons. These tracers eliminated the blinding effect on gunners at night and made the origin of tracer fire harder to determine.

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DBX - Depth Bomb Explosive. USN solid explosive developed during World War II to replace Torpex and used mainly for depth charges. It is a mixture of TNT, cyclonite, ammonium nitrate and aluminum.

Density Factor - The weight of a projectile measured in pounds divided by the cube of its caliber measured in inches. For example, the USN 16" (40.64 cm) AP Mark 8 weighed 2,700 lbs. (1,224.7 kg). The density factor of this projectile is thus 2,700 / 163 = 0.659.

Detonator - An explosive device used to set off a larger explosive, such as a blasting cap used to set off TNT.

Distance Piece - This is usually a rectangular cardboard piece folded into a triangular shape and placed into the cartridge case between the wad and the case closure plug or projectile. The distance piece is used to hold the propellant firmly in place when the amount of propellant does not completely fill the cartridge case. Distance pieces are generally used in fixed and semi-fixed ammunition for 40 mm and larger projectiles.

DPICM - Dual Purpose Improved Conventional Munition. A submunition carried as payload in projectiles such as the USN 5" (12.7 cm) Cargo Round. "Dual Purpose" refers to the munition having both anti-personnel and anti-armor capabilities.

Drag - The effect of air resistance on a projectile. Drag (D) = f(V/A) * K * Ø * P * Di2 * V2, where f(V/A) is a coefficient related to the ratio of the velocity of the projectile to the velocity of sound in the medium through which it travels. Sound through air at 68°F (20°C) at sea level travels at 1,128.6 fps (344 mps). K is a constant for the shape of the projectile. Ø is a constant for yaw (deviation from linear flight). P is the density of the medium, Di is the diameter (caliber) of the projectile, and V the velocity. The degree to which a projectile is slowed by drag is called retardation (r) given by the formula: r = D / M, where M is the mass of the projectile. Drag is also influenced by the spin of the projectile. The faster the spin, the less likely a projectile will "yaw" or turn sideways and tumble. However, if the projectile spins too fast, it will not "turn over" at the top of its trajectory (apogee) and so will not strike the target nose-first.

Driving Band or Rotating Band - A raised ring or rings of soft metal encircling a projectile designed for rifled gun barrels. Bands are normally located near the base of the projectile. The bands engage the rifling in the gun barrel, causing the projectile to spin as it travels through the barrel. Additionally, they provide a tight seal so that the propellant gases do not escape past the projectile, help to center the rear end of the projectile in the bore and hold the projectile in place during loading and gun elevation. Bands are typically made of copper, brass or soft steel. USN driving bands on large caliber projectiles were an alloy consisting of 97.5% copper and 2.5% nickel. An "augmented driving band" or "augmented rotating band" is a slightly thicker strip of metal used when the rifling in the gun barrel has been worn down to the point that a standard driving band is no longer effective.

Eccentricity - Distance from the geometric center line of a projectile to the center of gravity of the projectile.

EXE - Extra Experimental. British propellant of the 1880s that was a mixture of two-thirds brown powder and one-third black powder. This was used for a few 6-inch (15.2 cm) guns for a brief time, but the heavy smoke it produced made it difficult to use.

Explosive Train - An explosive train uses the impulse of an initiating explosive to start the chain reaction that leads to the detonation of a main burster charge or ignition of a propellant. For example, a fuze may be initiated by a firing pin striking a small mercury fulminate detonator charge which then sets off a booster charge which in turn sets off the main explosive charge.

F or FF - Form Factor. A value used for ballistic calculations. See "Ballistic Coefficient" above.

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Fixed Ammunition - Ammunition in which the cartridge case is attached to the projectile, similar to a pistol bullet. This type is usually limited to smaller weapons as the weight becomes prohibitive for hand-worked guns as the caliber increases past about 4 inches (10.2 cm). On my datapages for guns firing this type of ammunition, the value given for "Weight of Complete Round" refers to the total of the individual weights of the projectile, cartridge case, propellant and igniter all added together. The weight of the projectile itself is given separately if available. Also see "Bag" above and "Semi-fixed/Separate" below.

Flechette - A small fin-stabilized projectile. Usually used in large numbers inside of a single carrier projectile.

Fuze Setter
1) A machine located on or near the gun platform that is used to set time fuzes, usually for AA projectiles.
2) A gun crewman whose job it is to either operate the Fuze Setter machine or, by using a wrench or similar tool, to manually set projectile time fuzes.

Fuze Setting in the Hoist - Hoist fuze setting was first successfully accomplished by the USN with its 5"/38 (12.7 cm) when coupled with the Mark 37 GFCS. In this system, the projectiles were inserted nose down into a cup on an endless chain hoist that led from the handling room directly below the mount up to the gun breeches. As the projectile traveled up the hoist, a pawl in the cup, driven by the GFCS, would engage a lug on the projectile's time fuze ring. The cup rotated the pawl so as to set the time fuze. The time fuze setting was automatically and continually adjusted during the hoist as the firing solution changed. Loaders were trained to wait until the last possible moment before removing a projectile and placing it on the loading tray so as to get the best possible time adjustment.

Fuze Setting at the Muzzle - Muzzle fuze setting is normally done by induction. The fuze setter itself consists of a ring around the muzzle that generates a weak pulsed-electromagnetic field. As the fuze passes through the ring, it senses this data signal and sets itself accordingly.

Gaine (Booster) - An explosive container detonated by the fuze and which in turn detonates the bursting charge.

Grain
1) A measure of weight used in the UK and USA for small propellant charges and for the weight of small caliber bullets. 1 pound = 7,000 grains. 1 gram = 15.432 grains.
2) An individual particle of propellant. See "Powder Grain" below.

Greenboy - Improved British AP projectile developed late in World War I. The ballistic cap for these projectiles was painted green to distinguish them from older models, hence the nickname. Following the failure of British AP projectiles to detonate properly during the 1915 Battle of Jutland (Skagerrak), the Royal Navy began an intensive effort to produce better versions. These were introduced into service starting in 1918 and had a new delay-action base fuze patterned after the ones used on German 28 cm Psgr. APC projectiles. Greenboys had better armor penetration abilities compared to the older models, thanks to an improved body and the new "Hadfield" hardened AP cap.

Grommet - Cover used to protect the projectile rotating band during handling. The grommet is removed before the projectile is fired.

Head Length - The length of the projectile's nose. Same as "Ballistic Length." See "crh" above.

HMX - Cyclotetramethylenetetranitramine. A white crystalline powder used as a high energy oxidizer in propellants and explosives.

Hood - Thin cap used on USN Special Common projectiles to attach the windshield to the projectile body.

Hygroscopic - Literally means "water seeking" and is used to describe a material that readily absorbs water (usually from the atmosphere).

Igniter or Igniter Patch - Bag ammunition charges have a small patch at one or both ends containing black powder (gunpowder). This is used to set off the main propellant charge. See "primer" below.

K Device and A.K. Device - British designations for projectiles using dye bags. K devices had a dye container with a small explosive charge and a fuze which triggered upon water impact. These were used for 6 to 16 inch (15.2 to 40.6 cm) projectiles with the exception of the older 7.5 inch (19 cm) guns which were not issued dye projectiles. A.K. devices were used for 4.5 to 5.25 inch (11.4 to 13.3 cm) projectiles. A.K. Devices did not use an explosive charge. Instead, the ballistic cap had forward and aft ports sealed with brass plugs. Water impact forced out the plugs and water entered through the forward ports, mixed with the dye, and then exited through the aft ports. Red, Yellow and Green dyes were made, with White being available by simply not providing a dye. See "Splash Colors" below.

Lead Foil - A piece of lead foil is sometimes inserted at the top of the propellant in a cartridge case. The lead foil aids in scouring away residue left from the driving bands or unburnt propellant.

Lifting Plug - Threaded eyebolt which fits into the fuze cavity (nose or base), permitting heavy shells to be handled by means of a winch.

Link - The part of an ammunition belt which joins the individual rounds together. Usually, one link holds one round. "Disintegrating Link" means that the links holding each individual round to the next round separate from each other and from the cartridge as each round is fired.

Mercury Fulminate - An initiating explosive that may be used as either a primer or a detonator. It may be detonated by flame, friction or percussion and may in turn ignite a booster or it may be mixed with other materials to form a primer composition to ignite a propellant charge. Its melting point is too high to allow it to be cast and so it is usually loaded by being pressed into caps. It is affected by high heat and will decompose in storage at tropical temperatures such that at the end of three years it becomes useless. Its color is light yellow.

Meplat - The flat or blunt area at the tip of a projectile. Usually specified by its diameter.

MT - Mechanical Time. Designation for Time Fuzes used by the US Navy. See "Fuze" above.

NACO - Navy Cool. A cooler-burning propellant currently in use by the US Navy.

NCT - Nitrocellulose Tubular.

Nitrated Cotton - A short-fibered cotton bleached and purified to the point where it is 90% pure cellulose. This material forms the basis for nitrocellulose used in propellants. See "Propellants" below.

Nose Plug - The Lifting Plug (see above) used for nose-fuzed projectiles.

Nutation - The aerodynamic, gyroscopic and inertial forces acting on a spinning projectile are in constant flux as it travels through the air. As the various forces readjust themselves, the nose of the projectile describes a small arc around the axis of travel. This motion is called "nutation" from the Greek word for "nodding," which is a good description of what the projectile actually does.

Obturator - In projectiles, this is a band, usually made of nylon, below the driving bands. The band helps prevent propellant gasses from escaping past the projectile as it travels up the gun barrel. Commonly described as the "Forward Obturator" or "Forward Located Slip Obturator" to distinguish it from the breech obturator.

Gun_Data_projectile_pic.jpg
Ogive - The curved area making up the nose of a projectile. Usually defined as extending rearwards from the tip of the projectile's nose to the main cylindrical portion or bearing surface. From an ordnance manual: "Often a convex solid of revolution generated by an arc of a circle whose center lies on the side of the axis of revolution opposite to the arc." Whew, glad I found that out! In layman's terms, the head of the projectile is usually bullet-shaped. See "crh" above.

Oxidizer - Reactive compound which gains electrons during an oxidation-reduction chemical reaction. In propellants, this is the ingredient that provides oxygen for the burning process.

Palliser Projectile - Iron armor piercing shells of the mid to late 19th century which were hardened by casting the projectiles point downwards and forming the heads in an iron mold. This process rapidly chilled the hot metal of the nose and made it intensely hard. The remainder of the projectile mold was formed of sand, allowing the metal of the shell body to cool more slowly, making it tough but not brittle. These shells were powder-filled, but did not use a fuze. Instead, they relied upon the shock of striking the target to set off the burster. These shells were effective against wrought iron armor, but shattered against steel armor. Named after the inventor, Sir William Palliser.

PBX - Plastic Bonded Explosive. A mixture of cyclonite, HMX, PETN and a plastic binder. Has high mechanical strength, excellent chemical stability and is shock resistant.

PETN - Pentaerythritol tetranitrate. Shock-sensitive material used in explosives, blasting caps and in some mono-propellants.

Posit or Pozit Fuze - See "Fuzes" above.

Powder Bags - See Bag Ammunition, above.

Gun_Data_USN_Grain_pic.jpg
Powder Grain - An individual unit of propellant. Commonly used in the form of strips by France, cords (strings) by Britain and Japan, hollow tubes (single perforation) by Germany and Italy, and in multi-perforated cylinders by the USA, as shown at right. A propellant grain with a decreasing burning surface will tend to generate less propellant gas as it burns while a propellant grain with an increasing burning surface will tend to generate more propellant gas as it burns. Propellant grains whose total burning surface area decreases as they burn are known as degressive or regressive grains. Propellant grains formed in balls, cords, pellets and thin sheets burn degressively. Degressive grains are best used in weapons having a short barrel length as there is less need to maintain a steady pressure as the round travels up the barrel. A neutral burning grain is one whose total burning surface remains approximately constant as it burns. Single perforated grains and star perforations are examples of neutral burning grains. Technically, grains formed in sheets or strips burn degressively, but the change in burning surface is so small that these may be considered to be as effectively neutral burning. A progressive grain is one whose total burning surface increases as it burns. Grains with multiple perforations and those in rosette shapes burn progressively. A progressively burning grain has an advantage in a longer-caliber gun as more gas is generated to fill the increasing volume as the projectile travels down the barrel.

Pre-fragmented - A projectile, usually AA or antipersonnel, that has been sectioned so as to break up into uniformly-sized pieces when the round detonates.

Primer - A device used to provide a flame for the purpose of setting fire to a propellant charge. Also called an "igniter." Primers are divided into two types, depending upon the type of ammunition used by the gun: 1) Case and 2) Lock. Case primers, as their name implies, are used for guns firing case ammunition. These are small containers of an explosive such as mercury fulminate that are installed into the base of the cartridge case. Lock primers are used for bag guns and are inserted by hand into the firing lock of the gun. Primers are also divided into three classes, depending upon the method of firing: 1) Percussion, 2) Electric and 3) Combination. Percussion primers are fired by the mechanical impact of a firing pin. Electric primers are fired by passing a current through a resistance element surrounded by an initiating mixture. Combination primers may be fired by either of these methods, which allows for a mechanical backup if the electrical supply system to the gun fails.

Prismatic Powder - In 1860 General Thomas Jackson Rodman of the United States Army, realizing the advantages to be gained by increasing the propellant burn time, proposed the use of large grains of very dense black powder for this purpose. As a result of his research, he also proposed that perforated grains be used in order that the burning surface of each grain might be increased as combustion proceeded. The use of these grains gave a means of better regulating the ballistic action of black powders, and thus reduced undesirable items such as fluctuations in muzzle velocity. Different grain forms were tried, such as spherohexagonal and various prismatic shapes, including the hexagonal prism with a single perforation. The latter form was widely used in larger guns. The use of such grains was the first notable advance in securing a powder which would burn progressively, that is, with increasing evolution of gases and heat.

Puff - Non-explosive projectile used for training spotters. These produce a dense cloud of smoke approximately the size of those produced by high-explosive projectiles.

Reduced Charge - Smaller than normal amount of propellant. These may be used for practice firings as they reduce the amount of barrel wear per shot. They are also useful for shore bombardment missions, as the lower muzzle velocity and shorter range resulting when using these charges means an increased angle of fall and thus an increased horizontal penetration capability. This is also useful in striking reverse-slope defenses.

Rim - The lip or flange around the case head on a cartridge case which provides purchase for the extractor claw.

Ring Fuze - See "Fuze" above.

RLG - Rifle Large Grain. This was British large grained black powder, with the grains roughly 0.25 inches (6.4 mm) in diameter. RLG2 and RLG4 were later developments with still larger grains, with the largest being about 0.50 inches (12.7 mm) in diameter.

Rotating Band - See "Driving Band" above.

Sabot - Pronounced "sa-BO." Literally means "hoof" in French. This is a lightweight carrier into which a projectile smaller than the barrel diameter (usually called a sub-caliber round) is centered. The carrier fills the bore of the weapon from which the projectile is fired and is normally discarded a short distance from the muzzle. There are two common uses for this type of ammunition. The first use is when the projectile is made from a very heavy, dense material, such as in tungsten penetrators. Making the projectile smaller than the barrel diameter keeps the shell weight about the same as that of a conventional projectile and thus does not overstress the gun barrel. The second use is to give a light-weight projectile a higher muzzle velocity. This means that the same amount of propellant will throw the smaller projectile a longer distance than it will the conventional projectile.

Sankaidan - Japanese for "fragmentation." Also known as "incendiary shrapnel shells" (shôi ryûsandan). These were AA rounds which contained hundreds of incendiary-filled steel tubes and officially designated as "Type 3 Common Shells" (3 Shiki tsûjôdan). The incendiary filling was "Elektron" metal (45%), barium nitrate (40%) and rubber (14.3%) together with sulfur (0.5%) and stearic acid (0.2%). "Elektron" was a trade name for a metal alloy composed primarily of magnesium (90%) with the balance being aluminum (3%), copper (3%), zinc (2%) and silicon (2%). Besides their incendiary effect, the steel tubes also acted as shrapnel. The Type 3 was first deployed in 1942 for 20 cm (8 in) and larger guns and in 1943 for the 12.7 cm/40 (5 in) AA and 12.7 cm/50 (5 in) DP guns. The 46 cm (18.1 in) Type 3 projectiles for the Yamato class battleships may have been nicknamed "The Beehive" but this could be apocryphal. A time fuze was used to set the desired bursting distance, usually about 1,000 meters (1,100 yards) after leaving the muzzle. These projectiles were designed to burst in a 20 degree cone extending towards the oncoming aircraft with the projectile shell itself being destroyed by a bursting charge to increase the quantity of steel splinters. The incendiary tubes ignited about half a second later and burned for five seconds at 3,000 degrees C, producing a flame about 5 meters (16 feet) long. These shells were thought to have a larger lethal radius than did standard HE AA rounds. The concept behind these shells was that the ship would put up a barrage pattern through which an attacking aircraft would have to fly. However, the USN pilots considered them to be little more than fireworks and not an effective AA weapon.

SD - Sectional Density. A value used for ballistic calculations. See "Ballistic Coefficient" above.

Semi-fixed and/or Separate Ammunition - Semi-fixed ammunition is when the projectile and cartridge case are separate pieces but are joined together prior to firing. This term has become interchangeable with separate ammunition, which is where the projectile does not attach to the cartridge case but they are both rammed together into the breech. These types of ammunition were commonly used for AAA and DP type weapons used in World War II as this allowed each piece to be light enough to be manually handled. For example, the US 5"/38 (12.7 cm) Mark 12 used a projectile with a separate brass cartridge case which held the propellant. These were laid together in the gun's loading tray after which a rammer pushed them "home" into the breech which then closed automatically. Technically, the 5"/38 (12.7 cm) used separate ammunition, but most descriptions of this weapon, including USN official ones, use the term semi-fixed. In more recent years, the USN has adopted the term "Separate Ammunition" as the preferred description.

Set-back - The shock on a projectile when fired from a gun or when it strikes a target. Used to enable many fuze mechanisms such as impact and time fuzes.

Shalloon - See "Bag Ammunition" above.

Shark - A British ASW projectile developed near the end of World War II. Weighed about 96 lbs. (43.5 kg) and could be fired from any 4 inch (10.2 cm) gun. Not known if successful in battle, but trial results were considered to be very encouraging.

Shell Length - This is sometimes designated as being in "calibers," similar to barrel length. For instance, if a 16 inch (40.64 cm) shell is listed as being 4 calibers long, then this means that it is about 16 x 4 = 64 inches (1.626 m) long from nose to base.

Short Delay Fuze - See "Contact Fuze" above.

Shot - An archaic term for a solid projectile intended for penetrating armor. Mostly replaced by AP after about 1900.

Gun_Data_Shrapnel_pic.jpg
Shrapnel - Also known as "spherical case," this was a type of anti-personnel ammunition which consisted of a shell containing metal balls in the front and a small bursting charge at the rear which was detonated by a time fuze set to explode just before reaching the target. This was first adopted by the British Army in 1803 and is named after the inventor, Lt. (later General) Henry Scrapnel (sometimes spelled as "Shrapnel") of the British Army. This term has been used in the past to define shell fragments from most kinds of bursting projectiles, not necessarily anti-personnel types. Currently, the more accurate term "shell splinter" is in general use.

SP - Small Pebble. Large grain, densely packed gunpowder that replaced RLG. This was manufactured by using black powder tightly pressed into a block and then broken into small pieces or "pebbles" or cut into cubes of about 0.5 inches (1.27 cm) in size. P2 was a larger size cube of 1.5 inches (3.8 cm). See "Prismatic Powder" above.

Spin - A standard, fin-less projectile must be spun in order to maintain stability in flight. Under or over spun projectiles will tend to tumble in flight or not turn over at apogee and thus do not achieve good range or penetration performance. Generally speaking, the larger the diameter or longer the projectile, the slower it can be spun, in terms of rotations per second (RPS), in order to maintain stability.

Splash Colors - In group actions, when more than one ship is firing on the same target, it is difficult to determine which shell splashes are from which ship. This is important to know in order for each ship to be able to adjust its fire onto the target. The solution was "Splash Colors," first used by the USN during Force Battle Practice in 1930 and in use by most navies during World War II. The void space between the armor piercing cap and the windshield for AP projectiles was filled with a colored dye by the shell manufacturer. The dye is seen when the shell impacts in the sea and colors the resulting splash - hence the name. By using different colors, each ship could distinguish between their shells and those fired by other warships. In the USN, the dye was a dry powder which was packaged in paper bags. Interestingly, the USN used this dye to compensate for minor weight variations that crept in during the projectile manufacturing process. For example, the 16 inch (40.64 cm) Mark 8 AP had a nominal 1.5 lbs. (0.68 kg) dye bag, but this was allowed to be as large as 3.0 lbs. (1.36 kg) in order to bring underweight projectiles up to the standard weight of 2,700 lbs. (1,225 kg). Usually, a particular color was assigned to each ship. For example, the colors used by the USS Iowa (BB-61) class battleships were as follows:

USS Iowa - Orange
USS New Jersey - Blue
USS Missouri - Red
USS Wisconsin - Green

Splinter - Fragments of a shell after detonation.

Squib - A firing device that burns with a flash and is used for igniting black powder or pellet powder.

Star Shell - See "Illum" above.

Super Quick Fuze - See "Fuze" above.

Time Fuze - See "Fuze" above.

TP-T - Target/Practice projectile with Tracer.

TTB - Target Triggered Burst. See "Fuze" above.

Torpex - "Torpedo Explosive" used by the USN during World War II. Torpex is composed of 42% RDX, 40% TNT and 18% powdered aluminium. Its explosive power is approximately 50% greater than TNT alone.

VD - Variable Delay. USN terminology for base fuzes designed for armor-piercing projectiles. Complete designation was "VDXF" where "X" was the Mark number and "F" stood for fuze. See "Fuze" above.

VT - Variable Time. See "Fuze" above.

Wad - For cartridge cases using a loose powder propellant which does not fill the cartridge, a cardboard disc is placed on top of the powder and held with a distance piece to keep the propellant firmly in place.

​


Windshield - See "Ballistic Cap" above.

World War I Projectile Weight - Typical World War I AP caps weighed about 5% of the total projectile weight. World War I windscreens, when used, were tiny, only about 0.5-2% of the projectile weight. The need for increased range caused more World War II-like long windscreens to be added to some projectiles by the end of World War I. Burster weight was about 2.5-4% for APC, 4-6% for Common, 6-11% for HE and about 8-10% for CPC.

World War II Projectile Weight - Windscreens weighed 3-5% (depending on length) for most World War II projectiles, though German post-1930 L/4,4 and L/4,6 AP projectiles used brittle aluminum windscreens that only weighed about 1% of the total projectile weight. Hoods weighed about 5%. AP caps had more variable weights, with 8-14% being the usual range for large projectiles. Smaller projectiles, especially U.S. Navy 6 inch (15.2 cm) and 8 in (20.3 cm) AP projectiles, had much heavier caps. The U.S. Navy 335 lbs. (152 kg) 8 inch (20.3 cm) Mark 21 AP projectile had about a 17% cap weight, while the 130 lbs. (59 kg) 6 inch (15.2 cm) Mark 35 AP projectile had a 19-22% cap weight - both of these projectiles had the bluntest, most-hemispherical nose shapes of all projectiles in use. Explosives made up about 2-5% for APC, although the USN used about 1.5% in their "super-heavy" projectiles. HE or HC projectiles had about 6-8% explosive. Some exact breakdowns:

USN 16 inch (40.64 cm) 2,700 lbs. (1,225 kg) AP Mark 8 Mod 6 (Data from NPG Report 3-47)
AP cap: 312 lbs. (141.5 kg) [11.6%]
Windscreen: 32.4 lbs. (14.7 kg) [1.2%]
Bursting charge: 40.5 lbs. (18.4 kg) [1.5%]
Body weight (including bursting charge): 2,355.6 lbs. (1,068.5 kg) [87.2%]

German 40.64 cm (16 inch) 2,271 lbs. (1,030 kg) Psgr. L/4,4 (mhb) (Data from NPG Report 101)
AP cap: 363 lbs. (164.7 kg) [16%]
Windscreen: 27 lbs. (12.3 kg) [1.2%]
Bursting charge: About 53.4 lbs. (24.2 kg) [2.3%]
Body weight (including bursting charge): 1,880 lbs. (852.8 kg) [82.8%]

Definitions and Information about Naval Guns - Part 2
 
Miscellaneous Definitions

AAA - Anti-Aircraft Artillery. Generally, any AA weapon with a bore larger than about 2.5 inches (6.4 cm).

AAW - Anti-Aircraft Warfare or Anti-Aircraft Weapon.

ACTH - Arbitrary Correction To Hit. Empirical correction, based upon an analysis of previous firings, in range or deflection to compensate for indeterminate errors in the fire control solution.

Admiralty Table - British term during the mid-twentieth century for analog computers used to calculate firing solutions.

All Burnt - The point during a projectile's travel up the gun barrel where all of the propellant charge has been consumed. In most instances, propellant charges are designed such that the propellant has been consumed by the time that the projectile is about one half to two thirds of the way up the barrel. For example, the standard charge in a 5"/54 (12.7 cm) Mark 67 cartridge achieves All Burnt between 115 to 125 inches (290 to 320 cm) of shot travel, depending upon the amount of propellant loaded in the lot of charges being fired. Shot travel in the 5"/54 is 235 inches (597 cm), which means that the All Burnt point is about half-way up the barrel. There are a few exceptions where the All Burnt point is further up the barrel, but these are usually for rounds developed after the gun entered service where the charge developers are trying to obtain the highest possible muzzle velocity.

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All Steel - A British term of the 1930s and 1940s used to describe guns built primarily from forged castings. This term was used to distinguish these new weapons from older guns built using wire winding techniques. The first large caliber British "all steel" gun was the 12"/50 (30.5 cm) Mark XIV, which was an experimental weapon completed in August 1933 to test the new construction techniques. The successful completion of these tests led to the same techniques being used to construct the 14"/45 (36.6 cm) Mark VII guns used on the King George V class battleships. It should be noted that wire-wound guns built for the Royal Navy had Wire engraved on their breeches while all-steel guns had Steel engraved on their breeches.

Angle of Fall - The angle with respect to the horizontal that a projectile attains at the end of its ballistic flight. Horizontal is defined as 0 degrees and vertical as 90 degrees.

Angle of Obliquity - The angle at which a projectile hits a plate of armor. Perpendicular, with the axis of the projectile at right angles to the surface of the plate at the point of impact, is defined as being 0 degrees.

Armor Penetration Definitions - The ability of an Armor Piercing projectile to penetrate armor is defined as follows:

  • Rejected - The projectile fails to penetrate the plate.
  • Partial Penetration - For hits of less than 45° obliquity, the forward half of the shell penetrates the armor while the rear half is rejected. For hits over 45° obliquity, the nose and upper body are rejected while the broken lower body penetrates. This usually means that the projectile will not explode or will have a low-order detonation, but it will still inflict splinter damage on whatever is behind the armor plate.
  • Holing Limit - The maximum thickness of face hardened armor plate that can be damaged by a particular AP projectile. The projectile itself is rejected, but a plug of armor, usually of the diameter of the striking projectile, is pushed into the ship.
  • Naval Limit - The maximum thickness of armor where at least 80% of the projectile penetrates. Usually this means that the projectile is broken up and will probably not explode, but it will still inflict splinter damage on whatever is behind the armor plate.
  • Effective Limit - The maximum thickness of armor a projectile will penetrate relatively intact and still explode as intended.
Armor Thickness - The nominal thickness of American and British armor plates are not always equivalent. This is because of the "40 pound" rule. A steel plate exactly one inch thick (25.4 mm) and one foot square (30.48 cm sq.) weighs 40.8 lbs. (18.5 kg) for steel with a specific gravity of 7.85 g/cm3. For convenience and ease of calculating weight and cost, both the USN and the Royal Navy rounded this off as meaning that a plate one inch thick and one foot square weighed 40.0 lbs (18.1 kg). However, the thickness and weight of armor plate was interpreted and calculated differently by the designers of American and British warships. The USN specified armor plate by its thickness while the Royal Navy specified it by its weight. Thus, in the USN a "one inch thick" armor plate was defined as being 1.0 inches thick and thus actually weighed 40.8 lbs. (18.5 kg) per square foot. In contrast, in the Royal Navy, a "40 lbs. plate" was considered to weigh 40.0 lbs. (18.1 kg) per square foot and thus was nominally 0.98 inches (2.49 cm) thick. What this means is that when you see an armor thickness on a USN warship given as being 10 inches (25.4 cm) then this means that the plate would have a nominal thickness of 10.0 inches (25.4 cm) but an armor plate on a British warship given as "400 lbs." means that it had a nominal thickness of 9.8 inches (24.9 cm). Most sources would say that both ships had armor thickness of 10 inches (25.4 cm), but this is not strictly correct as the armor of the British ship would be nominally 9.8 inches (24.9 cm) thick. However, please note the repeated use of the word nominal in this definition. The manufacturing of armor plate is a complicated, involved process requiring many different steps with each subject to some level of variability even in the most tightly controlled environment. USN acceptance standards usually included about a +/- 2.0% thickness tolerance due to this normal manufacturing variability, so USN plates with a nominal thickness of 10.0 inches (25.4 cm) could actually range from 9.8 inches up to 10.2 inches thick (24.9 to 25.9 cm). The Royal Navy had similar tolerances and when these tolerances are taken into account it can easily be seen that a British "400 lbs." plate on the thick side could actually have a greater thickness than a USN "10-inch plate" on the thin side.
ASuW - Anti-Surface [ship] Warfare or Anti-Surface Weapon.

ASW - Anti-Submarine Warfare or Anti-Submarine Weapon.

Auto Control or Automatic Control - USN terminology meaning that the guns are being pointed at the target via data transferred electromechanically from the fire control computer (rangekeeper) system without manual input. See "Local Control" below.

Automatic vs. Semi-Automatic vs. Manual Firing - Automatic firing means that as long as the trigger or firing switch is closed, the gun will continue to pump out rounds. An example of this would be a machine-gun. Semi-Automatic means that the trigger or firing switch must be cycled for each shell fired, but that all shell handling operations are performed without manual intervention. An example of this operation would be a magazine fed pistol. Manual means that each individual shell must be handled and rammed into the breech by the gun crew in order to fire. An example of this would be a single-shot bolt action rifle. A "semi-automatic" breech is one in which the breech must be closed manually after the round is rammed, but when the gun fires the breech opens by itself and ejects the spent shell casing (cartridge). A "fully automatic" breech is one in which the breech mechanism closes by itself when the round is rammed as well as opening and ejecting the shell casing automatically after the weapon fires.

Base Slap - When an armor piercing projectile hits an armored plate at an angle, there is a tendency for the shell to "yaw" or tilt as it pierces the plate. This tilt, if large enough, can result in the end of the shell - the base - hitting against the edges of the shell hole. The impact can cause the shell to break up and thus not detonate properly. Base slap also refers to when a shell hits a plate at such a large angle of obliquity that it starts to ricochet. As the nose of the projectile bounces off, the base of the shell slams down onto the armor plate, which again can cause it to break up or detonate prematurely. See "Hammer Action" below.

WNUS_5-38_mk12_Bennington_pic.jpg
Batten Board - This is a screen used for bore-sighting guns when a point target is not available. The board is set up at a specific distance from the gun or, as can be seen on the adjacent photograph, attached at a specific point on the gun barrel. On the screen there will usually be at least four points, one for the bore sight, one for the trainer's sight, one for the pointer's sight and one for the sight checker's sight. These points are marked at exactly the same distance from each other that they are on the gun being boresighted. On the batten board in the picture at right, the long vertical stripes were used to adjust the gunsights such that they remained in parallel with the barrel as it elevated. See "Bore Sighting" below.

Battle Ranges - The gun ranges at which navies expected to fight grew dramatically during the first half of the twentieth century. By 1900, most navies considered 1,000 yards to be the maximum range at which battles would be fought, although the 1898 Battle of Santiago during the Spanish-American War was fought at ranges up to 9,500 yards. In 1903, the US Navy thought of 3,000 yards as being the probable battle range. Most of the major naval battles in 1905 during the Russo-Japanese War took place at ranges between 3,000 and 9,000 yards. A British naval observer of those battles, Capt. William Pakenham, concluded that superior British gunnery should allow fire to be opened at 20,000 yards and that 10,000 yards would be seen as close range. However, in 1905 the famous battleship HMS Dreadnought was designed to fight at 6,000 yards. By 1907, US battleships were being designed to fight at 8,000 to 10,000 yards. In December 1910 the Chief of the US Bureau of Ordnance was quoted in Brassy as stating that 12,000 yards was the maximum battle limit as "at 15,000 yards all or nearly all of the actual hull of the [target] was below the horizon." This referred to the view from turret gunsights; a spotter 90 feet up could see nearly twice as far. In 1911 the battleship USS Delaware was able to repeatedly hit the obsolete USS San Marcos (ex-Texas) at 16,000 yards by utilizing such a spotter technique. In 1914 the British considered that "very long range" fire would commence at 15,000 yards for ships with 13.5" guns and at 13,000 yards for ships with 12" guns. However, at the Battle of Dogger Bank in January 1915, British ships opened fire at ranges of about 20,000 yards and were able to score hits even though their range finders were inaccurate at any range over about 15,000 yards. The USS South Dakota (BB-49) class of 1918 was designed for battle at 18,000 yards or more and when USS North Carolina (BB-55) was designed in the mid-1930s, she was expected to open fire at 24,000 yards.

Battery
1) A weapon is said to be "in battery" when it is at rest in its mounting, ready for firing. This term comes from the days of muzzle loading cannon where the gun was fired and was allowed to recoil back far enough such that it could be swabbed, loaded, rammed and then moved forward back into firing position or "returned to battery." See "run out," below.
2) All of the guns of a specific caliber on a particular ship. For example, the term "Main Battery" for USS Iowa BB-61 refers to her nine 16-inch (40.64 cm) cannons while the term "Secondary Battery" refers to her 5 inch (12.7 cm) guns.
3) All weapons that can be trained on a particular target regardless of their caliber, as in the phrase "a battery of weapons."

Biting Angle - The maximum angle of obliquity where an AP projectile will penetrate an armor plate rather than ricocheting.

Blowback
1) Unintended escape, to the rear and under pressure, of the propellant gasses. Blowback may be caused by a defective breech mechanism, a ruptured cartridge or a faulty primer.
2) Gasses formed by burning propellant which are used to cycle the breech mechanism of gas-operated automatic weapons.

Bore Premature - An explosive projectile detonating prior to leaving the gun barrel.

WNUS_3-50_mk2_Ockenfels_pic.jpg
Bore Sighting - Aligning the bore of a gun with the gunsights. For guns that operate only in local control, this is usually achieved by first inserting a bore telescope into the breech of the weapon, as can be seen in the photograph at right. The bore sight is adjusted such that its cross hairs are exactly aligned with cross hairs that have been attached to the muzzle. The gun is then aimed until the bore sight is centered on a point target, preferably one that is at a similar distance where the gun would be most effective. The gun sights are then adjusted until they are centered on the same target point. See "Batten Board" above.

Bracket - A succession of two salvos, one over and one short or one left and one right, with no straddles.

Bracket Salvo - A method used to determine the range to a target. This procedure was extensively used by the German Navy in both World Wars. As used by the Germans, three half salvos were fired. The first half salvo was fired at the range determined by the rangefinder, the second at a range 400 meters too long and the third at a range 400 meters too short. By seeing which half salvo lands closest to the target, the actual range and bearing can be determined.

Broadside - Firing in a single salvo all guns that can bear on an abeam target. This may involve more than one caliber of weapons.

BuOrd - USN Bureau of Ordnance. The Bureau of Ordnance and Hydrography was established on 31 August 1842 and changed to the Bureau of Ordnance (BuOrd) on 5 July 1862. The Bureau of Ordnance was abolished on 18 August 1959 when its functions were transferred to the Bureau of Naval Weapons (BuWeps). BuWeps was replaced by Naval Ordnance Systems Command which was established on 1 May 1966. This command and the Naval Ship Systems Command were combined to become the Naval Sea Systems Command which was established on 1 July 1974.

CEP - Circular Error Probable. Although a friend of mine insists that it really stands for "Circle of Equal Probability." Half of the data points fall within a circle of this radius centered on the MPI (or target, depending upon the the subject), half lie outside of this circle. For example, for an eight shell salvo, the CEP would be the radius of the circle containing the four shells that impacted closest to the MPI.

Charge Assessment - The process of determining the propellant weight necessary to achieve nominal new gun velocity for specific lot of propellant. When a new lot of propellant is produced a series of test firings is conducted to determine the correct charge assessment. This process is called powder proof. Current practice is to fire a series of tests in three or four different gun barrels. Charge weight is varied and pressure and velocity is recorded for each shot. See "Proof" below.

Chase Hooped - A method of strengthening weak gun barrels. Basically, this involves shrinking on additional hoops over the chase of a gun barrel.

Chicago Piano - Originally in the 1920s and 1930s, this was a slang term referring to the Thompson 0.45 caliber sub-machine gun, supposedly the weapon of choice of Chicago gangsters. During World War II, this was then used as a nickname often applied to almost any multi-barreled AA gun, most commonly to the British 2-pdr, British quad 0.50" andUSN 1.1" AA guns. In the book "Whispering Death" by Lee Heide, there is a mention of a German naval AA weapon with this nickname, but the internal information in this book would lead me to believe that this was actually the Italian 37 mm AA gun.

Clip - A length of metal which holds several rounds together for feeding into a weapon. The rounds are usually stripped off the clip by the bolt as it cycles.

Cold Gun Correction - Refers to a correction for range for the first shot from a gun. The first round from a gun falls slightly short due to the reduced friction caused by the oil used to swab the bore to keep it from rusting. This reduced friction allows the projectile to move forward at a lower pressure than what occurs in a clean, dry bore, and this lower pressure results in a lower muzzle velocity. Fire control systems have a built-in adjustment for this condition.

Collective Fire - When the whole battery of a single ship, which may consist of more than one caliber, fires at the same target.

Gun_Data_concentration_dial_pic.jpg
Concentration Dial or Range Clock - In many ship photographs taken between about 1916 and 1940, there are what appear to be large clocks on the front and rear superstructures or masts. These are actually devices to tell the other ships in the formation at what range that ship is firing at. Together with Declination Marks (see below), these mechanisms allowed the other ships in the formation, whose view of the target may be obscured by fog, gun smoke or funnel smoke, to have their guns at the proper elevation and bearing when their view becomes unobstructed. This greatly reduced the time needed before they were ready to fire. The introduction of radar and better ship-to-ship communication methods in the late 1930s eliminated the need for these devices and they were removed from most ships by the start of World War II or shortly thereafter. For the concentration dial shown here, the small hand represents the range in thousands of yards, with 0 = 10,000 yards and 9 = 19,000 yards. The big hand represents range in hundreds of yards.

Concentration Fire - When two or more ships fire on the same target.

Continuous Fire - Firing is not stopped for spots or corrections. Usually applies only to ships having automatic control of guns or when the target solution is considered to be exceptionally good, such as when the target has been repeatedly hit by previous salvos. See "Rapid Fire" and "Slow Fire" below.

Continuous Fire, Rapid - Each gun in each turret or at each position fires when loaded and ready without waiting for the other guns.

Cook-off - Unintended firing of a weapon. A gun barrel becomes very hot after a prolonged period of firing. This heat can cause propellant in the firing chamber to become hot enough to spontaneously combust and thus unintentionally fire the weapon. This is one of the reasons why many automatic weapons are "bolt open" designs that do not chamber a round until after the trigger mechanism is activated.

Copper Choke - Most rifled guns of the nineteenth and twentieth centuries used projectiles having copper driving bands. When fired, copper rubbed off these bands will form deposits on the rifling of the gun barrel. These deposits can build up over time as the gun is fired and will narrow down the bore. The increased friction caused by this narrowing - "choking" - will slow down subsequent projectiles and thus increases the barrel pressure, often to dangerous levels that can damage or split the barrel. Most navies developed a procedure of regularly cleaning the barrels with wire or pisaba brushes in order to remove these deposits. See "Fouling" and "Steel Choke" below.

COTS - Commercial Off The Shelf. Using existing components and technology rather than developing new ones.

CTL - Constructive Total Loss. Something so badly damaged that it is uneconomical to repair it.

Cue Balling - One of the major "sailor alts" (see below) used to increase the rate of fire of 8 inch (20.3 cm) guns on US cruisers of the World War II period. This involved using the rammer at high speed to strike the projectile and bat it into the breech. This meant that the rammer did not have to extend and retract past the much shorter and thus faster acting powder bag ram position. This unofficial loading method increased the ROF of these weapons from the standard 3 RPM up to 5 or 6 RPM, a significant improvement. The fact that the gun crews were able to do this on a regular basis and not damage the mechanisms is a credit to the designers of the mountings, who over engineered them to be resistant to such abuse.

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DAMS and DEMS - British designations meaning "Defensively Armed Merchant Ship," used during World War I, and "Defensively Equipped Merchant Ship," used during World War II. This terminology was an attempt by the British to circumvent those treaty provisions that allowed submarines to attack any armed merchant ship without warning.

Danger Space - That distance in front of the target, measured parallel to the line of fire, that the target could be moved toward the firing point, so that a shot striking the base (waterline) of the target in its original position would strike the top of the target in its new position. The flatter the trajectory, the greater the danger space. See "Hitting Space," below.

Davis Gun - During World War I, the USN conducted a series of experiments in mounting larger caliber guns on patrol aircraft for anti-submarine use. The "Davis non-recoil Guns" were 6-pdr (57 mm) and 3" (7.62 cm) weapons having two barrels. The first barrel faced forward and fired a standard projectile while the second barrel faced directly backwards and fired bird shot or buckshot. The weapon fired both barrels simultaneously, thus negating the recoil motions. A Lewis machine-gun was mounted alongside these weapons to aid in spotting. Named after the inventor, Cmdr. Cleland Davis, USN.

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Declination Marks - Scales painted on a turret mount to indicate to other ships in the formation the direction in which the turret is pointing. See photograph of HMS Emperor of India (IWM SP 1743) at right. See "Concentration Dial" above.

Deflagration - Very rapid combustion sometimes accompanied by flame, sparks and/or spattering of burning particles. Deflagration, although classed as an explosion, generally implies the burning of a substance with self-contained oxygen so that the reaction zone advances into the unreacted material at less than the velocity of sound in the material. In this case, heat is transferred from the reacted to the unreacted material by conduction and convection. Burning rate is usually less than 2,000 meters per second.

Deflection - Lateral angular correction applied to target bearing to bring fire onto a target. Most targets move, so it is necessary to "lead" them so that the projectile will arrive at their future position. See "LOF" and "LOS" below.

Detonation, Low Order - The condition when a bursting charge does not fully combust or combusts inefficiently. This can be the result of a projectile being damaged when striking the target, such as when an AP projectile passes through armor.

Dispersion - The distance from the point of impact of a particular projectile to the MPI of the salvo. Dispersion in range is measured parallel to the line of fire and dispersion in deflection is measured at right angles to the line of fire. A Dispersion Pattern is the combining of all the impact points of a particular salvo.

Drift, Angular - The angle between the bore axis of a weapon and the target. See "LOF" and "Trajectory" below.

Drift, Linear - The lateral deviation of a projectile in flight caused by the rotation of the projectile. See "LOF" and "Trajectory" below.

Elevation - Moving a gun along its vertical axis.

Equal Section Charge - Propellant charge made up of a number of small charges equal in size. Making multiple small individual charges makes them easier to handle than one large charge. The number of sections used determines the muzzle velocity and range of the projectile.

Erosion - Wearing away of a bore due to combined effect of gas washing, scouring and mechanical abrasion. The greatest source of wear is from the propellant gasses, which corrode the rifling via heat and chemical action.

FCS - Fire Control System. This usually refers to all elements involved in pointing the guns at a target from the range finder to the rangekeeper to the elevating and training mechanisms for the guns themselves.

Feed - How ammunition is supplied to a weapon.

FKC - Fuze Control Clock. A simplified version of the British HACS. See HACS essay on the Technical Board for further information.

Flare-back - When a gun is fired, smoldering remnants and unburned propellant or propellant gasses can be left in the chamber. When the gun breech is opened, the sudden infusion of oxygen can cause these to ignite, sending flame back into the gun housing. Many large caliber weapons used a purging system which injected nitrogen gas into the chamber shortly after the gun was fired in order to extinguish and expel such particles. In movies or pictures of USN 16 inch (40.64 cm) guns, this nitrogen purging can be seen as a small puff of smoke that is emitted a few seconds after the gun fires.

Fouling - Deposits of metal in the bore of a gun from the jackets or rotating bands of projectiles. Sometimes also known as "copper choking." In the days of black powder guns, this was also the term used for the residue left in the gun barrel from unburned gunpowder.

fps - Feet per second.

GFCS - Gunfire Control System.

Gun Index / Turret Efficiency - Guns in multiple mounts always lose efficiency as compared with the same number of guns in single mounts. This is a factor of reduced rate of fire, handling awkwardness, interference between guns, fire control, salvo problems and so forth. To account for these factors, there is a gun-index rule of thumb that goes like this: A twin mount is roughly 1.75 times as effective a single mount, a triple mount is roughly 2.5 times as effective as a single mount and a quadruple mount is roughly 3.125 times as effective as a single mount.

Gun Jump - Defined as the variation in the angle between the gun bore axis and the effective line of projectile departure. Round-to-round variations in the line of departure result from movement of the gun barrel during firing and round-to-round changes in barrel droop due to thermal heating. Investigations have shown that one of the primary causes of gun jump is bending oscillations during firing. Optical measurements have shown that gun barrels are driven into high frequency oscillation caused by the changes in gas pressure as the projectile travels down the barrel. This means that the particular oscillation phase existing at the instant when the projectile exits the barrel is passed on to the projectile. The barrel oscillation has the effect of causing the projectile to leave the muzzle at an angle (relative to the original axis of the bore) corresponding to the instantaneous oscillation phase. In addition, the projectile is given a transverse velocity which is proportional to the angular velocity of the barrel. Thus, gun jump has both a horizontal and vertical component. The horizontal component generally varies by one to two minutes of angle from round-to-round and accounts for a large part of the deflection dispersion. The mean of the horizontal component is generally zero; therefore allowance for it is not made in firing tables nor in the aim of the gun. The component of jump in the vertical plane does not average zero, as barrel droop changes with gun elevation, which changes the frequency of oscillation and the transverse velocity; therefore these effects are accounted for in firing tables and the aim of the gun.

HACS - High Altitude Control System. A series of British analog anti-aircraft fire control computers and directors of the late 1920s - 1940s period. See HACS essay on the Technical Board for further information.

Hammer Action - When a shell hits armor plate at a large angle of obliquity (usually about 25 to 30 degrees) there is a tendency for the shell to bend or whiplash as the nose of the shell abruptly slows down before the base does. This can cause the shell to break up, detonate prematurely or fail to penetrate. The name comes from the similarity of using a hammer to hit a nail head at an angle, rather than straight on. The nail usually gets bent over, rather than being driven into the wood. See "Base Slap" above.

Hangfire and Misfire - A hangfire is when there is an unexpected delay between when the trigger is pulled and the gun actually fires. This may be due to a slow burning primer, or, for bag guns, the powder bag may have been loaded backwards or it may have become crooked during loading, so there is a delay while the fire burns from the back of the bag to where the ignition pad is located. A misfire is when there is a complete failure to fire. It is impossible to tell a hangfire from a misfire until the gun breech is opened and the ammunition examined. For bag guns, an ember on the powder bag might smolder for a long time, so it is common practice to wait for 30 minutes before opening the breech.

Hitting Space - The distance behind the target, measured parallel to the line of fire, that a projectile striking the top of the target will strike the horizontal plane through the base (waterline) of the target. It may also include a distance in front of the target within which impacts are likely to produce underwater or ricochet hits upon the target. In other words, the hitting space is the distance between the point where a shell falling short of a target will start to inflict damage and the point at which a shell falling long of a target will stop inflicting damage. The greater the angle of fall, the smaller the hitting space. At long ranges, danger space and hitting space are about the same size, but at short distances the danger space is larger than the hitting space. See "Danger Space" above.

HSMST - High Speed Maneuvering Surface Target.

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Inclined - During an inclination test, a set of standard weights are run on rails across the beam of the ship. The amount of tilt (inclination) caused by moving the weights a certain amount can be used in calculations to determine how much the ship weighs. Various other factors - such as weight distribution fore and aft - can also be determined by moving the weights back and forth.

Indirect Fire - Firing at a target that cannot be seen. Usually refers to shore bombardments.

IS or ISE - Initial Salvo Error. The distance by which the first salvo missed the target.

Killer Tomato - Pictured at right, this is a large orange floating balloon that is used as a target during naval live fire exercises for guns. Other available inflatable targets include the "Killer Lemon" (yellow floating balloon), the "Killer Banana" (yellow towed target) and the "Bogie Blimp" (aerial balloon AA target).

Ladder Salvo - Also called "Ranging Salvo." When a ship is firing at a target and isn't quite sure of the range, what the gunnery officer will often do is elevate each gun or group of guns slightly differently. This makes each shell land a little farther along than the last one. By watching to see which shell hit or landed closest to the target, the range can be determined more accurately. During the early part of World War II, the procedure used by the new US battleships was to fire all nine guns as a ranging salvo, a typical pattern being one group (three guns from one turret) at 200 yards (180 m) up from the initial range estimate, one group at 200 yards (180 m) down and one group at 400 yards (370 m) down. There was also a timing difference between groups to avoid confusion between the shell splashes. Once a bracket had been obtained, thus indicating the correct range, the ship would then switch over to rapid fire, with the guns firing as they were ready.

Laying - As in "Laying the Guns." Setting the elevation and train of the guns such that the shells will land on target.

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Lead Angle - The difference between LOS and LOF is referred to as the "Lead Angle," as illustrated in the adjacent sketch.

Local Control - Guns are fired using only their co-located telescopes or open sights and do not use director or remote control. Values of range, deflection, and fuze settings are determined at the guns.

LOF - Line of Fire. The bearing and elevation you aim the weapon at to deliver fire onto the target's future position. Same as "Laying the Guns."

LOS - Line of Sight. The direct line between your weapon and the target's present position.

Measurement Units

  • Nautical Mile - Until relatively recently, a nautical mile was defined by Britain to be exactly 6,080 feet (1,853.184 m) long while the USA defined a nautical mile as being 6,080.2 feet (1,853.249 m) long. In 1929, the International Extraordinary Hydrographic Conference defined an "International Nautical Mile" as being exactly 1,852 meters (6,076.115 feet) in length. This standard was adopted by the USA in 1954 and by Britain in 1970. Under any of these standards, a nautical mile has been traditionally rounded off by English-speakers to 2,000 yards (1,828.8 m). When one reads in a British or USA publication of something being ten nautical miles away, it usually means a distance of 20,000 yards (18,288 m). A cable is normally defined as being one-tenth (0.1) of a nautical mile, although there is no internationally recognized definition.
  • Inch to Centimeter Conversions - From 1893 until 1959, the United States of America defined one meter to be exactly equal to 39.370 inches. This meant that the USA inch was equal to 2.54000508 cm. During that same period, Great Britain defined an Imperial inch to be equal to a 1/500,000 part of Earth's polar diameter, which meant that an Imperial inch was equal to 2.5399772 cm. In 1959, both nations adopted the "international inch" standard which defined one inch to be exactly equal to 2.540 cm. At this time, the US "mile" measurement changed to the new system, but "statue mile" remained at the old standard in order not to mandate changes to every US Geological Survey Map ever made. Thus, a "US mile" is still 5,280 feet (1,609.344000 m) long but a "US statue mile" is 5,280 "survey feet" (1,609.347219 m) long. On my datapages, the inch to metric conversion and vice versa is always given in international inch units.
  • Weight - In the USA and Britain, the displacement of a ship or the weight of a major ship component such as a turret was usually stated in "long tons" which is a measurement unit equal to 2,240 lbs. (1,016.047 kg). Other nations generally used "metric tonnes" for these purposes, which are 1,000 kg or 2,204.623 lbs. each. On my data pages, weights given in "tons" are long tons, while those given in "mt" are metric tonnes. It may be assumed that one British "Imperial" pound is essentially equivalent to one USA "avoirdupois" pound at any time after 1883, as the differences between them were trivial (about 1/10,000,000), although they were not officially made exactly equal until the United Kingdom approved the Weights and Measures Act of 1963.
Mil - A unit of angular measurement, defined by the US Army to be equal to 1/6,400 of a circle and by the US Navy to be equal to 3 minutes 26 seconds of arc.
MPI - Mean Point of Impact. The statistical midpoint of a salvo of projectiles. For example, if a circle is drawn around the shell splashes created by a single salvo, then the MPI would be the center point of that circle.

mps - Meters per second.

Muzzle Energy - The kinetic energy of a projectile as it leaves the muzzle of the gun. This is a product of the projectile's mass and velocity as calculated by the formula: ME = 0.5 * Mass * Velocity * Velocity. Muzzle energy should not be confused with momentum, which is calculated with the formula: Momentum = Mass * Velocity.

Muzzle Flash - Fireball seen when a gun fires. This glare is primarily the result of the ignition of unburned propellant gases as they exit the muzzle of the gun and mix with atmospheric oxygen. See Muzzle Flash essay on the Technical Board for further information.

NGFS or NGS - Naval Gunfire Support.

NSFS - Naval Surface Fire Support. Includes surface-to-surface missiles and other ship-borne ordnance as well as gunfire.

Offset Firing - A live firing exercise where a deflection error is entered into the calculations such that the projectiles land a predetermined distance to the left or right of the target ship.

OP - Ordnance Pamphlet. USN Bureau of Ordnance (BuOrd) document. Ordnance Pamphlets contain detailed information describing the operation and maintenance of ordnance equipment. A separate Ordnance Pamphlet is issued for each unit of ordnance equipment, such as guns, turrets, directors, etc. In addition, other Ordnance Pamphlets contain more general instructions or such data as range tables, nomenclature lists, scientific principles, etc.

OrdAlt - Ordnance Alteration. USN Bureau of Ordnance (BuOrd) document describing a change to an existing weapon, ammunition, mounting, etc. See "Sailor Alt" below.

Ordinate - Any point along a projectile's ballistic path. "Maximum Ordinate" is the highest point (apogee or summit) that the projectile attains during its flight.

Optronic - A combination of the words OPtical and elecTRONIC. Usually refers to an optical gunsight which has some means of computer-assisted aiming.

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Parbuckling Gear - As used in USA ships, a projectile moving system using powered capstans and ropes. "Parbuckling" is the process of moving the projectiles out of stowage and onto the shell hoists.

Pattern - The pattern of a salvo in range is that distance measured parallel to the line of fire between the shot that lands at the greatest distance from the firing ship and that that lands at the shortest distance, excluding wild shots. The pattern of a salvo in deflection is the distance measured at right angles to the line of fire between the shot landing farthest to the right and that landing the farthest to the left, excluding wild shots.

Pisaba Brush - Gun barrel cleaning device made with bristles from a type of palm frond. Usually mounted on a long pole or has ropes attached to each end so that it can be pushed and pulled through the gun barrel.

POH - Probability of Hit.

Proof or Proofed - As in "proof test."
1) After a gun is manufactured and has passed visual and non-firing tests, it is taken out to a gun range where it is fired with charges well above the maximum service charge. A gun having passed these tests is said to have been "proofed" or "proof tested." Proof testing for US Army cannons today consists of firing three standard rounds through the gun and then one "super slug." The standard rounds subject the cannon to typical stresses, while the super slug inflicts more severe stresses on the cannon than it would normally experience during its service life.
2) When ammunition is manufactured, a representative sample of each lot is fired to determine if it meets specification.

Range Clock - See "Concentration Dial" above.

Range, Gun and Navigational - Gun Range is the range set on the gunsights to obtain a hit. Navigational Range is the geometric distance between the firing ship and the target at the moment of firing. As the movement of both the firing ship and the target affects the point of impact, the Gun Range and the Navigational Range are seldom the same. These parameters are usually resolved by the firing ship's ballistic computer.

Range, Maximum - A gun does not always achieve its maximum range at an elevation of 45 degrees. This is because air friction will always alter the ballistic path that a projectile takes. For example, when large caliber guns with high muzzle velocities are fired at elevations greater than 45 degrees, their projectiles pass through thinner, more rarefied air. This reduces the air's total resistive effect on the projectiles throughout their flight time, allowing them to achieve greater ranges as a result.

Range, Slant
1) The distance in a straight line to an airborne object. In other words, the length of the hypotenuse of a triangle formed by the horizontal and vertical distances to the object.
2) The maximum distance a projectile can travel before it reaches its highest altitude (apogee). This is useful in gauging the performance of AA weapons as it represents the reasonable maximum range that an aircraft or missile can be engaged.

Range Finders, Optical - There are two basic types of optical rangefinders used on ships, coincidence and stereoscopic. The coincidence type splits the view into two separate sections, usually one above the other. The observer adjusts the rangefinder controls so as to move the two views into alignment in order to get the correct range. Coincidence rangefinders require an easily discernible line on the object being ranged in order to accurately measure the distance. The stereoscopic type works like binocular vision. If you do not have your eyes focused correctly, then the object you are looking at is blurred or doubled. When your eyes are focused correctly, the object appears clear and you have a good idea of the distance to that object. Stereoscopic rangefinders operate in a similar fashion. There are two separate images, one for each eye, that must be blended together in order to get the correct range. In USN systems, there were small diamond marks on the borders that were "moved" forwards or backwards until they appeared to be in focus at the same range as the target. Stereoscopic rangefinders generally give better results and are harder to "spoof" than coincidence rangefinders, but they require special aptitudes and a high degree of concentration on the part of the operator.

Rangekeeper - USN term for analog computers used in the first half of the twentieth century to calculate firing solutions. Replaced by simply "computer" in modern times.

Rapid Fire - The director fires whenever a certain number of turrets are ready. In case of rapid fire guns this is synonymous with continuous fire. See "Slow Fire" below.

RCS - Radar cross section. The measure of a target's ability to reflect radar signals in the direction of the radar receiver. The larger this value, the more energy that is reflected back to the radar receiver.

Ready-use Ammunition - Ammunition stored close to a gun instead of in a magazine. For larger guns located in open mounts, the rounds may be stored in bullet-proof steel lockers or racks. Many smaller guns have the ready rounds clipped to the inside of the gun shield for easy access.

Rocking Ladder - "Walking" the point of aim back and forth across the target, thus allowing for small errors in the firing solution. Often used for rapid fire and automatic weapons.

rpmpg - Rounds per minute per gun. A way of describing the rate of fire of each individual gun in a multi-gun mounting.

Run-out - The process of returning guns to battery after they have fired and recoiled. This term originates from the days of muzzle loading cannon where the cannons had to be withdrawn into the ship to be loaded and the crews had to then manually move the cannon back out the gun ports before they could be fired. Most large caliber weapons designed since 1880 utilize hydraulic and pneumatic run out systems although many smaller weapons such as machine guns use springs.

Safety Rails - On many warships with light, manually worked automatic weapons such as the 20 mm Oerlikon, there will be a railed structure surrounding the weapon. These are used to prevent the gun from being pointed in certain directions and thus prevent the gunner from accidentally firing into the ship itself. See "Wooded" below.

Sailor Alt - Unofficial USN term used to describe an unauthorized change to standard practice. See "Cue balling" and "OrdAlt" above.

Salvo - When two or more guns are fired.

Salvos, Half and Double - In some action accounts of British warships, there are references to "half salvos," "double salvos" and "broadsides." In this context, when referring to a ship armed with multiple two-gun turrets, a "half salvo" was when the ship simultaneously fired one gun from each turret. A "double salvo" was when one gun from each turret was fired, followed a few seconds later by the other gun. A "broadside" was when all guns were fired simultaneously. Half salvos were generally used for ranging purposes while double salvos were used once the range was known. Double salvos had the advantage of reducing shell interference at the cost of some lateral dispersion caused by the turret rotating under the off-axis force.

Siacci Method - A method of determining approximate ballistic performance developed in the late 1880s by Cornal Francesco Siacci of Italy. This method is useful only for low-angle trajectories (<15 degrees) and is commonly used today for calculating the performance of rifle-caliber bullets. The method reduces the calculations for a low-angle trajectory to an easily tabulated quadrature giving distance, time, inclination (flight path angle) and altitude (height) in terms of a "pseudo-velocity".

Slow Fire - Firing a salvo only after the one before it has landed and its spot has been applied to the firing solution. See "Rapid Fire" above.

Spall - Fragments broken from either surface of a barrier. For example, fragments broken from an armor plate as the result of projectile penetration, impact or detonation against the plate.

Steel Choke - Refers to a type of flaw found in British guns of the late 19th and early 20th century. "Choke" is an allusion to a type of shotgun barrel that has had the muzzle deliberately altered in size and shape in order to give a more desirable pattern spread. As the British started to use larger castings for their guns during the late 19th century, problems arose caused by the uneven cooling of the metal. One of these problems was that of the inner A tube closing in near the muzzle and then cracking. This was a result of longitudinal stresses in the tube being concentrated at the foremost locating shoulder. Various makeshift arrangements, including such things as cannelured rings to support the castings, improved the situation somewhat, but the problem was never really corrected until the introduction of a slow taper fit between the inner A and A tubes and changing the position of the locating shoulders of the A tube well back so as to better distribute the stress patterns. The later versions of the 13.5 in/45 (34.3 cm) Mark V were the first guns built with this solution. A similar "steel choke" problem was found on many older gun designs after prolonged firing. As in most guns, the continual drag of the projectile driving bands caused the liners of these guns to be gradually stretched forward. The resulting projection at the muzzle could be simply cut off, but in addition the liners began to form a ridge in the bore near the shoulders of the outer A tube. This ridge, sometimes known as "copper choke" as it tended to accumulate copper from the projectile driving bands, narrowed the bore and could cause enough drag to initiate the projectile fuze, with the result that a premature detonation would occur either within the bore or shortly after the projectile exited the muzzle. While this ridge could be filed down, the only permanent solution was to fit the guns with a new liner having a different arrangement of the internal shoulders and rifling.

Straddle - When a salvo lands on each side or all around the target. This indicates that the firing solution is correct and thus the next salvos may be fired without waiting for spot correction.

Star gauge - A simple measuring tool used for large caliber guns to determine the amount of liner wear at the start of the rifling in front of the forcing cone. This measurement is used to calculate the amount of liner life remaining.

Striking Angle - The angle at which a projectile hits a plate of armor. Perpendicular, with the axis of the projectile at right angles to the plate, is usually defined as being 90 degrees. With this definition, the striking angle is then the reciprocal of the angle of obliquity. In other words, if the striking angle is 50 degrees, then the angle of obliquity is 40 degrees.

Superelevation or Super Elevation - The angle the gun must be elevated above the line of sight in order to compensate for the effect of gravity acting on the projectiles in flight. See "Trajectory" below.

Swedish Additive - A mixture of titanium dioxide and wax that greatly reduces barrel wear. This mixture was extensively used aboard the US Iowa class battleships during their last activations where it was credited with at least quadrupling the liner life.

Synchronizing Time - The length of time required for a gun mounting to move to the elevation and train positions being sent from fire control.

Tachymetric - Literally means speed measurement, but in the British Royal Navy of the World War II era this word was used to describe a fire control system that automatically predicted the future position of an aircraft target in three dimensions.

Target Salvo - When the target's range is accurately known, all guns are fired at the same elevation, which makes all the shells land close together. This greatly increases the chance of a hit.

Tip-Off Angle - The tilt of a projectile away from the axis of the gun barrel as the projectile exits the muzzle. When the bourrelet of a projectile clears the gun muzzle, the front of the projectile is no longer receiving support from the gun barrel while the driving bands continue to support the rear of the projectile. This means that the force of gravity will try to rotate the projectile about its center of mass, which causes the nose to drop slightly. This tilting process continues as the projectile emerges from the barrel until the time that the driving bands exit, at which point the projectile is no longer receiving any support from the gun barrel. The result is that the axis of the projectile is no longer in parallel with the axis of the gun barrel. In other words, the nose ("tip") of the projectile is slightly askew ("off") from the center or axis of the gun barrel while the base of the projectile is still aligned with it. Asymmetrical differences in friction around the circumference of the muzzle (caused by erosion, thermal deformation or balloting) and strong cross winds can also produce tip-off forces. Tip-off angles are generally small, but they contribute to round-to-round dispersion.

TNT - Tri-nitro-toulene.

Torching - The burning of the combustible components of the residual gases in the cartridge case following extraction and exposure of the case and gases to oxygen. Hot surfaces on the cartridge case having temperatures in excess of 1,400 degrees F (760 degrees C) can cause ignition of the residual gasses.

Train
1) Moving a gun or mounting along its horizontal axis. Also called "traverse" or "traversing."
2) A line of gunpowder leading to an explosive charge within a shell. Usually called "explosive train."

Gun_Data_trajectory_pic.jpg
Trajectory - The path followed by a projectile in flight.

Ultimate Battery - During World War II, the USN made extensive plans as to what kind and how many of various weapons would be carried by each class of ship. This planned weapons set for a particular class of ship was known as its "ultimate battery." Due to shortages or changes in other areas, such as increased electronics, the "ultimate battery" was often changed or not reached during the war.

Ward-Leonard System - An adjustable speed drive for electric motors. Used for RPC, this system controls the DC voltages to the armature and the magnetic field strength with a simple algorithm, in which the desired torque and the magnetizing field strength served as command inputs. This system not only furnishes a very flexible and rapid control of heavy machinery, but also eliminates the power loss associated with the use of rheostats.

Wear Gauge - A truncated cone used on smaller guns to determine the liner life remaining. This is inserted into the breech end of the weapon.

Windage - The gap between the outer surface of a projectile and the surface of a smooth-bore gun. Projectiles must be slightly smaller than the gun bore in order to allow them to be easily loaded. Windage is not normally used to describe rifled weapons, as it is considered that the projectile driving band fills the gap.

Wild Shot - A projectile that lands abnormally far in deflection or range from the MPI.

"Wooded" and "Wooding" - When a gun or gun sight is pointed in a direction where its LOF or LOS is blocked by the ship's structure. This term comes from when ships were built of wood.



From "Ghostrider One" by Gerry Carroll, published by Simon & Schuster © 1993:

Battleships - Even though these great warships do not figure in this novel at all, I can't resist commenting on them. From the earliest days of naval warfare, even the dumbest commanders have known that the thing which is the number-one most important gotta-have-it asset in a fight is weight of metal on the enemy. You can screw up the tactics, but if you've got the biggest guns and the heaviest shells coming down on the bad guys accurately, you will probably win. There are all sorts of annoying exceptions to this rule, but it still holds most of its water.

The BBs were the rulers of the sea up until the Japanese took their little trip to Hawaii in 1941, then were supplanted by the carriers (out of sheer necessity since the American battleships had been abruptly turned into hazards to navigation). The battleships were relegated to a supporting roll and, except for getting dragged out of mothballs for every war we've had since World War II, were pretty much finished.

In the eighties, we recommissioned all four of our Iowa class battleships and deployed them around the world. They carried sixteen-inch guns and fired rounds weighing around 2,700 pounds apiece. The effect was like shooting an entire showroom full of Ford Escorts, packed with high explosive, about twenty-five miles. When the rounds hit, they made instant holes in civilization that were the size of tennis courts. I got to see the New Jersey fire a broadside at somebody in Beirut once, and I still haven't found the words to describe it.

This was also effective because the people who were fired upon immediately quit annoying their neighbors and repaired to their graves. The surviving terrorists went home for an underwear change and all was quiet for awhile.

The battleships have all been mothballed again now and it doesn't seem the same anymore. When one sees a battleship steaming along, one is seeing Navy and all that that meant through the centuries. There is no weapon on earth that will make a little tinpot dictator sit up and take notice like a battleship slowly cruising off his coast well out of pistola range with her guns trained on his presidential palace. It sort of gives him a little peek at his relative importance in the grand scheme of things. If that peek stops one firefight, however small, or saves one life, or ensures the fairness of one election, then the battleship has earned her keep.

But, since those things usually happen outside the Capital Beltway, and Dan Rather doesn't mention them, they matter not at all to the geniuses in Washington. Those events have no bearing on the next election, and every congressman knows that money to measure the effect of cow farts on the ozone layer is far more important than wasting it on a battleship. They're quite correct, too. It'll help next year, when the bill to teach cows to say "excuse me" comes out of committee.
Definitions and Information about Naval Guns - Part 3
 
Mexican Navy Orders Naval Guns from BAE Systems
Jun 24th, 2014


Mexican-Navy-Orders-Naval-Guns-from-BAE-Systems.jpg

BAE Systems has been awarded a contract to produce and deliver four 57 Mk3 Naval Guns to the Mexican Navy.

“This contract award further strengthens our strong position in the naval guns market,” said Lena Gillström, managing director of Weapon Systems, Sweden, at BAE Systems. “This competitive win shows that BAE Systems’ world-leading 57mm naval gun and ammunition systems continue to be selected as the best solution for both new and existing customers around the world.”

The 57 Mk3 gun is proving to be a successful product for various customers. In addition to Mexico, the 57 Mk3 is also in service with Navies and Coast Guards in the United States, Canada, Sweden, Finland, and Malaysia.

The 57 Mk3 gun can fire four rounds per second and can switch immediately between ammunition types to deliver seamless targeting of air, land, and sea-based threats and provide superb survivability and tactical freedom at all levels of conflict.

Series production begins immediately, with gun deliveries beginning in 2015 and continuing through 2017. Final assembly will take place at BAE Systems’ facility in Karlskoga, Sweden.

Mexican Navy Orders Naval Guns from BAE Systems >> Naval Today
 
A new variant of artillery system AK-630M
PQsmZCo9Byc.jpg

and AK-630M2
7piSSBNZH_s.jpg
 
vostok said:
A new variant of artillery system AK-630M
PQsmZCo9Byc.jpg

and AK-630M2
7piSSBNZH_s.jpg
Click to expand...

I sincerely wonder why not more navy's that already have single-cluster AK630 haven't yet upgraded to 'Duet'. Or why e.g. the batch 2 Talwars and their cousins being built for FRS navy don't get this (since they no longer get Kashtan but rather single cluter AK630).
 
Again I am trolling with my photoshps:)

Dear Members
Why still navyies use artillery with hi-tech missiles? Why dont give up artillery?
Because artillery is most cheap and economical method. But they havent guided systems.

Missiles have guieding systems but they are very expensive. SOM or Tomahawk cruise missile nearly 1 million$.



Nowadays we have 300mm and 600mm artillery rockets with range 100km and 300km.

Without guiding systems artilery rockets cheaper than missiles. GPS guided systems also cheap( if am not not wrong )50K$.

Let's produce cheap, mini destroyers. :)
I created it for the against Greece islands, radars and air defence systems. May be for Syria or Egypt or Israel.
10 NAVAL MLRS Ships with our frigates and corvettes can destroye every objects.
Also This is for security of our coast.

Naval Mlrs.jpg


French Ofshore Patrol Vessel L Adroit.
Front and Back sides opened and has a lot of space for the launchers.
French_Navy_Offshore_Patrol_Ship_P725_Adroit.jpg
 
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