Spring airsoft guns or rifles are single-shot bb guns, that use potential energy stored in a spring to launch a pellet down the barrel of the airsoft gun. You must cock the gun or rifle prior to each shot, much like you would a real shotgun or bolt-action rifle. This is usually done by pulling back the slide, which compresses the spring and makes the airsoft gun ready to fire. Because of this, these airsoft guns are incapable of automatic or semi-automatic fire.