Most mass shootings and gun related deaths in general are committed with standard issue handguns and not AR-15s. AR-15s are also semi-automatic and firing at the exact same rate as a handgun, which is also semi-automatic. Meaning they both fire one round per squeeze of the trigger. Banning one type of weapon some mass shooters use wouldn't stop what's causing them to commit these awful acts in the first place. You have to find the route of what causes them to want to kill. Because if they want to kill people, they will use a different weapon to do so. AR-15s are also not military weapons. They were designed for civilian use. Military uses fully automatic weapons like M4s and their family of weapons. Which aren't legal in most cases to be owned by a civilian.