It then reloads a fresh shell or cartridge from the magazine into the chamber and cocks the gun. Semi-automatic guns do this automatically when they fire. Although a semi-automatic will fire only one cartridge per trigger pull, an automatic will continue to fire cartridges as long as the trigger is pulled. An automatic is also known as a machine gun. It is estimated that the majority of these weapons remain in circulation.
Handguns can be either revolvers or semi-automatic pistols.
Revolvers have a round cylinder that is actually the magazine and acts as a chamber when properly aligned with the barrel. In double-action revolvers, each time the trigger is pulled the weapon fires and the cylinder advances to the next chamber. Single-action revolvers require that the hammer be manually cocked before each shot. A revolver's cylinder usually holds six cartridges. Spring pressure forces the cartridges upward in the magazine.