You CAN'T put prior restraints on fundamental rights, like the second amendment. (If you want to repeal it first, then I say go for it). You can't any more license guns, constitutionally, than you can license speech. The second amendment is the FIRST among equals in the bill or rights. Without it, all other rights are meaningless in the face of a despot or tyrant who takes control of the gov't (domestic OR foreign). Your are focusing on PRAGMATIC or prudential arguments. They have no relevance whatsoever to gun rights UNTIL SUCH TIME that you repeal the 2nd amendment. You can't require training for gun ownership any more than you can require training to exercise your free speech rights, your freedom of religion rights, assembly rights, etc. Certainly there are costs associated with any and all rights, just like we have to put up with KKK, you name it, to preserve speech rights. The RKBA is much much bigger than small societal costs. We're talking about keeping our people from becoming slaves, or keeping minorities from becoming exterminated, as Hitler did in Germany. This are the rare, but monumentally adverse tyrannical conditions that we have private ownership of guns to guard against. Small societal costs, (if ANY on a net basis, which is quite arguable), pale in comparison to keeping our nation free. The price of freedom is eternal vigilance. Moreover, in the Hitler/Paul Pot/Stalin, etc., etc. scenario, what guns do you think will work best against standing armies (mercenaries, foreign or domestic)? Handguns? They're better than nothing, but not nearly as good as automatic military weapons in the hands of citizens (the militia). The second amendment protects military weapons, including fully automatic small arms. Interestingly enough, it probably does NOT protect very small handguns like derringers, as they are marginally useful, if at all, to a military group or citizen's militia. I could go on and on, but you've got to look at a macro scale - the big picture of history - not just small prudential arguments (99% of the time, the prudential arguments weigh heavily in favor of gun ownership anyway - look at Lott's research - on a net basis, the more guns carried by citizens, the less the societal costs due to greatly decreased crime. Also, arms most useful to a citizen's militia - military style repeating rifles - are very rarely used in crimes, anyway).