I hate using Wikipedia as a source, but so be it.
I think it's interesting to note that while we're in the top fifteen for gun related deaths -- and we're also #1 for guns per 100 residents -- we're nowhere near leading the charts for gun related homicides. This will sound callous, but I'm not too concerned about gun related suicides when it comes to gun control. I've always been a fan of suicide reform laws.
As for gun control itself, and I speak as someone who's dad used to own a 9mm and a rifle and some other gun he never used (which, unbeknownst to him, I had easy access to), I think the "answer" is a lot harder than "get rid of the guns" or "leave gun control laws alone," or even "tighten gun laws."
Speaking from a non-utilitarian standpoint for half a second -- even if mass murderers only had access to a glock, that's still the death of three or four compared to ten - fifteen.
If we examine the mindset behind these crimes -- because getting rid of guns will solve nothing, this kind of killer will only seek other methods (the Columbine killers original plan was to blow up their school and kill off the survivors as they escaped (and we all know how easy it is to make a bomb with a copy of the Anarchist's Cookbook and a basic understanding of structures)) -- I think we could go a lot farther in eliminating mass shootings like this.
That being said, I wouldn't mind tightening gun laws in the way of making it harder to obtain a gun. We require tests for driving and flying airplanes and joining the military and everything else. I think guns should be the same. If you want an AK-47, prove that you're mentally fit to own one, why you should own one, and get re-tested every year. Same for all adults in the household with access to the gun. And gun insurance, IMO, should be mandatory -- going up for each member of the household in case one of their guns causes the death of another.
That does little to solve gun violence in gang related crimes and shootings where the guy steals his mom's guns, but there really is no simple answer unless we just want to eliminate all guns. I don't think that will solve much in the case of where most of our gun violence comes from, but it might get rid of a few trigger happy George Zimmermans.
But I think it's very telling that the first things people jump to blame are non-neurotypical people, atheists, video-games, and inanimate objects. Always arguments about gun control, but never anything about preventing the source of the crime from even developing (and I don't mean rooting out psychopaths (and not all psychopaths are killers) and taking them out at birth) -- the mind of the killer. No one is born a killer (though it is debatable that some are born psychopaths).