Bruce Schneier makes reference to a good point about crazy people, spree killings and body armour. Basically, the NRA's theory goes, if there's some bad guy out there with a gun, we want a good guy with a gun there to deter them from doing anything. But when that good guy's gun is rendered useless by the bad guy wearing body armour, what do you do? Arm the good guys with armour-piercing rounds?
Ned Kelly is an Australian icon not for the horse he rode, or the guns he used or even the stage coaches he robbed. We remember him because of his armour, and now much better armour is available over the counter to anyone who doesn't want to get shot. That's good, but when we live in a world that encourages us all to go around armoured everywhere, we've lost something. When the sheer proliferation of guns means that everyone needs to be both carrying their own weapon and armour all the time, we are one very tiny step away from a kind of neo-feudalism and knights roaming the streets in a concrete kingdom. That is not where we want to be.
Mokalus of Borg
PS - Some people do need access to weapons.
PPS - Those people are far fewer in number than many people assume.