Yeah that's BS.
You are not shooting 1000m with a 0.308 in combat, with the best scope in the world. I can (now after about a 1000 rounds in marlin) certainly hit 500-600 m mark every time, 800m if you are Chris Kyle Level (shot placement wise, not Jigra wise), 1000m there is no guarantee with the best shooter Carlos EFFIN Hathcock. If 0.308's could handle 1000m shots, thee would be no need for .338 lapua, 300 winmags or 6.5 creedmoors .
7.62x51N effective shootable range is about 600-800m, beyond that I doub't its repeat ability, sure it still will posses energy to kill, but in combat repeat ability is a must. i have seen .308's tumble and slice silhouettes in a paper as low as 750 yards.