Semi-Automatic
A firearm that fires one round per trigger pull and uses recoil or gas to chamber the next.
Also: semi-auto, self-loading
A semi-automatic firearm fires one round each time the trigger is pulled, automatically loading the next round from the magazine. The energy for cycling comes from the fired round itself — usually via gas tapped from the barrel or recoil acting on the slide. Semi-autos are the dominant action type for modern handguns and sporting rifles.