It's not the gun laws that are the problem. Obviously it's a huge factor, but if someone is that mental that they'd want to go out and shoot a few dozen people, then they're gunna have no problem with illegally acquiring a gun. Even here in Australia, anyone can get a firearm, it's not so hard; heck if I wanted one, I could probably have it within a week. Ofcourse the law is preventing me, but tell me, what does a psychopath who's just shot his own mother, 20 kids, and 7 other people, as well as himself, have to fear from the law?
The problem lies in the culture that's ingrained in people from a young age. Especially in the US, violence is a normal thing. If you've got a tree that's bugging you, you pull it out from the roots, you don't just chop off the uppermost leaves. Same with 'banning' guns, it won't do anything. You have to deal with the problem from its roots.