What I don't understand about gun control laws is how it would deter someone from shooting up an entire school (for example). A person hellbent on shooting up an entire school or workplace is already intent on committing as many murders as they can before they're caught or kill themselves. Clearly they weren't planning on following a law that says murder is illegal, so why should they care about a law that says having a gun is illegal?
If the argument is that a gun control law would make it more difficult to get their hands on guns, I will concede that point. I'm also fairly certain a 'black market' for guns would spring up just as it has done for drugs. Then it becomes an academic question of how pissed off someone is to find a dealer before they can start shooting.
For me, it's a comfort that there might be a citizen nearby that chooses to have a concealed carry or other firearm, such that if someone does start shooting up a mall, it's possible I don't have to rely on rent-a-cops that frequently don't have anything but a handheld radio to deter an armed person.