bohm,
Nugget does make a valid point, to quote "However, what you can do is make it harder for them to cause harm." (In the same manner , if a burglar really wants to get into your house, he will - no matter what you do. That fact, though, does not mean we despairingly throw our hands up in the air and leave our homes unlocked. We can and do implement measures to make it harder for a would be thief - even if it only serves to make him move on to easier pickings!)
There will always be violence, guns or no guns. However, the contribution firearms have made has been to make violence more deadly - which is why they were introduced in the first place. (The destruction one person armed with an AK-47 is capable of carrying out is out of all proportion to what that same individual could do if he were armed with nothing more than a chunk of rock or a length of timber!)
We can, though - as nugget says - make it harder for disturbed individuals to get hold of a firearm;
-such measures as requiring guns to be kept locked in secure containers, or vetting of firearms owners for mental instability, criminal records etc. (Down in this part of the world, that is what we have to do -and speaking for myself, a licensed firearm owner, I have never had a problem with that).
Bill.