How about this? Statistics show that guns are used in self defense apprx. 2 million times a year, saving atleast but not limited to one person per use. In 2010, 8,775 murders were caused by someone using a firearm.http://http://www.guardian.co.uk/new...crime-us-state
Also in 2010 there was a total of 12996 murders.
Basically, what I'm saying is that in 2010, more lives were saved by firearms than were taken by firearms. Even the total number of murders in general wasn't even close to overcoming the amount of people saved by using firearms in self defense.
You also asked what is causing these mass murders if not guns? I guess I hadn't mentioned that point because I thought it was obvious.
IMO the problem is clinically insane people going out and killing people. Which is a healthcare issue IMO. If these insane people didn't have guns, then they would still be able to mass murder. If guns didn't have crazy people to operate them, then they literally can't kill anyone(accidental discharges excluded). It's not the guns doing the killing. Gun's are merely a tool. These people who have clear psychiatric problems need to be addressed more and need to be taken serious. Not just prescribed a huge dose of anti depressants and then forgot about.
Even if guns were banned you could never get rid of all of them. So thinking that getting rid of them will remedy the problem is absolute nonsense. Who cares how hard it is for a criminal to get a gun, if the end result is them getting a gun and mass killing people who were defenseless? The fact that it was hard for him to get that gun would have made absolutely no difference. He was dead set on doing what he did, and he would have found a way to carry out his plan regardless, and the fact that people ignore this is beyond me.