I don't know. Everyone wants to talk about guns. And I don't think we should have the kind of guns that can do what that guy did yesterday. And I think the assault gun ban should not have been allowed to expire. But frankly, I don't know shit from shinola about guns, and if you make one mistake a gun lover will jump in and say "hmmmmmmm. yet, that ban would not have stopped yesterday's masacre because he used a 1346.156 and the ban only banned the 1346.157! Dummy! you should find out the facts before you go on one of your knee-jerk gun-grabbing rampages" And they will think they have proved some point.
What I really wonder about is the culture that produces such people as this young man, and produces them quite regularly. And it is that same culture that produces gun-worshippers, and violence, and mass murderers. And installs leaders who worship violence and the killing of innocents, and who start wars.
Everyone wants someone to blame, and we'd all like to blame the guy who did it. But he's dead, and we can't kill him twice, though many of us would like to. So everyone will blame whoever we can, without ever once looking into the mirror, and wondering if there is any blame there.