The guy who went to New York with his guns proved that. Who knows what evil lurks in the hearts of men.
Maybe a lie detector should be part of the process to getting a gun? Or the class you have to take to carry maybe the class you need to take just to own one.
You need to take the class to get a hunting license now. Didn't when I was a kid. But you do now. Is that unconstitutional?
Or how about, if you commit a violent crime....you go to prison. For ever. You know, control the element that is the most easily controlled.