Every time Hillary attends an even, odds are good that the Secret Service runs attendees thru metal detectors. THAT is the only thing that might have prevented this shooting in the first place, but he also could have just shot up a school bus. In other words, all the legislation and all the precautions in the world generally won't prevent a shooting, but an armed response can cut it short. But the gun grabbers would rather pine for their delusional utopian fantasyland of a world without guns.
Let’s see - guns used were a revolver and a shotgun, both of which would have been unaffected by a semi-auto ban.