Assault Weapon- (n) noun
Any
semi-automatic firearm, due to modification or malfunction and not repaired, that fires more than once when the trigger is pulled and released once.
Revolvers and shotguns are not assault weapons. BB,
pellet, and paintball guns are not firearms according to
the ATF.
AR-15 is not an
assault weapon. AR stands for the trade name brand
Armalite Rifle.
AR-15 with a bumpstock would be an assault weapon.
M16A2 and M4 are assault weapons. They have the option for safe, semi, and burst. Burst option fires 2-3 times when the trigger is pulled once.
Machine Guns are not assault weapons. They are designed with a high fire rate when the trigger is pulled.