My take is that if their law allows it, its their choice to carry a gun. The idea of opening a gun store to convince people not to buy guns is interesting, but the arguments they use are the same and flawed.
For example, children hurting others with guns. Well, I know of an incident where a child stabbed his brother to death with a kitchen knife.
Boy, 12, stabbed baby brother to death | Daily Mail Online
Then, the Sandy Hook shooter - that guy could have done the same with a glass bottle and some gasoline if he wanted to. All a gun did was make his work a little easier. The real issue is still in the minds, the mental capability of someone to actually commit murder like that. If they're that crazy, they'll just find a way to do it without guns. If he could shoot his mother, how hard do you think it'd be for him to steal some gasoline and make a crude bomb with it?
And criminals, actual, proper criminals, will get guns no matter how much you restrict them. Or anything for that matter.
I am in favour of civilians owning weapons. But mental health checks should be mandatory for issuing a license; it is feasible for a country like America to implement that if they want to keep their guns but reduce these kinds of incidents. Also, an age limit. No one who isn't allowed to drive should be allowed to hold a weapon (referring to the 9 year old girl who shot her instructor with an Uzi).