Semi-auto handguns, or semi-automatic pistols, are handguns that use the energy from the prior shot to reload the chamber for the next shot, so that the gun can be fired with each pull of the trigger.  A detachable magazine supplies the ammunition. Popular brands of semi-automatic pistols are: Glock, Smith & Wesson (or S&W), Sig Sauer, Springfield, and Ruger. The benefit of the semi-automatic pistol is that they are quick firing and have a magazine that can be exchanged quickly.