Timothy McVeigh killed 168 with a truck.  Terrorists in 2001 killed thousands with planes.  If one wants to kill large numbers of people guns are a relatively inefficient tool.  Las Vegas was the height of mass shootings in this country, and doesn't come close to a major terror incident.  How many people realize just how easy it is to create a phosgene gas infusion into a  ventilation system?  Cry if you want about taking everyone's guns away, it will not stop mass killings.