The pin hits the cartridge, firing the bullet down the barrel. When each barrel revolves around to the bottom with the cylinder, the expended cartridge shell falls outside of an ejection port. Most machine guns hire the gasoline produced with the explosion in the cartridge to generate the mechanism https://machinegunphoenix61594.shoutmyblog.com/37251484/5-simple-statements-about-sig-spear-lt-explained