A semi-automatic rifle is a type of rifle that fires a single bullet each time the trigger is pulled, without the need manually to operate a bolt, lever, pump or other firing or loading mechanism. Such a rifle can fire single rounds like this until the firearm's bullets in the cartridges is gone. On the other hand, a "fully" automatic weapon (a machine gun, for example) keeps firing until the trigger is released, and can fire hundreds of shots for every trigger press.