Gun control laws will only effect law-abiding citizens. People with something to lose will think twice before they violate the law. Criminals who utilize guns don't care. A person who will participate in criminal activity that already carries severe sentences isn't going to be deterred by a gun control law.
Good point. So good, in fact, I just came up with a new bumper sticker: "When Guns Are Outlawed, Only Outlaws Will Have Guns" ;-)