I would say that our crime rate has more to do with our social dynamic than with the prevalence of firearms. Other countries like Canada and Switzerland do not have any of the social issues we in the US have to contend with. It is true that by limiting freedoms in general there is a greater propensity for social limits, and the mindset of most of the citizens of these much more PHRASECENSOREDPOSTERSHOULDKNOWBETTER. countries are much more subservient than ours is.
In Australia, there are quite a few people who are legally registered to own certain firearms, and there are quite a few more who own them illegally. Gun crimes still occur regularly here, perhaps not to the same proportion as they do back home, but most of the more seasoned Aussies I deal with admit that it is still quite easy to acquire a firearm here if you want one. I've had the opportunity in the 6 months I've been here to buy a gun if I wanted to. The gangs here are well armed, and drug crime here is not much different epidemiologically than it is back home.
As for whether diminishing the supply would have any impact on violent crime back home, I doubt it. Just this last friday, some idiot lit off two bombs at my daughter's high school, one equipped with C4 that failed to go off fortunately. Where there's a will, there's a way, and the last group in a society to be disarmed would be the criminals.
If the criminals here can't get their hands on firearms, then they use knives, or clubs, or whatever they can make work. Knives are also outlawed here, yet it is becoming the weapon d' jour for the gang kids.
It isn't the tools they use, it is the will they have, that will make people a threat to each other. We'll kill each other with sticks and rocks and even our bare hands if that's all we are allowed, but the killing will continue nonetheless. Doesn't seem much point in outlawing one if you aren't going to outlaw the lot.
Compare the gun control of today to the gangster days of the thirtys. We've gotten much more restrictive, yet the crime rate today towers over what it was back then. Obviously it isn't the prevalence of the weapons, but the willingness to use them that is the problem.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)