I am a gun nut, and I think the way most of the states of the US go about gun control. For the most part anyone can own a firearm aside from class III weapons, and each purchase has at the minimum a background check.
Criminals, crazies and those who are just out for vengeance will obtain means of performing their acts without it being legal to obtain or not. And like others said, gun control laws only affect those who obey laws altogether. People will also find ways to abuse ANYTHING, regardless of the legality; the car didn't chose to hit someone, the knife didn't choose to stab someone, the gun didn't chose to shoot someone. The person in control of each decided that for himself. Granted, guns are solely meant to do harm, but that doesn't mean no one can have one. Drugs are meant to alter something within your body, doesn't mean they should be outlawed too because its possible to take it too far.
I believe even without owning a firearm a citizen is protected by the right to own one. An everyday criminal out to perform a mugging won't know for sure if his intended victim is armed or not. A criminal in a country with strict gun laws has a pretty good chance of committing his act unresisted whether it be a simple mugging, or the robbing of a bank.