> If the United States ever got serious about banning firearms, a massive homebrew industry would grow up overnight.
Do you have any stats or experience to back that up? It might happen, but you are stating as fact something that's not been tested.
Anecdotally, in Australia where gun laws are very strict, it's difficult to get firearms. Yes, serious hardened criminals still get their hands on them, which certainly is a problem.
The average angry Joe can not simply legally purchase a semi automatic or handgun to walk around to his antagonists house and shoot them.
With a murder rate twice any other developed country[1], the United States clearly has a serious violence problem, and taking guns out of the hands of the average Joe would surely help reduce it.
[1]http://en.wikipedia.org/wiki/List_of_countries_by_intentiona...
Using the argument of "Hardened criminals will still get them anyway" is like saying we shouldn't have a law against murder because some people will do it anyway, so it's a waste of time. The point is to deter or make it extremely difficult for as many people as possible.