The central mechanism of a firearm, generally applied to rifles. It consists of the receiver, a short hollow tube of metal with cutouts to accept the other functional parts of the weapon. These include the barrel, for directing the bullet; the magazine, for feeding rounds into the chamber; the trigger, for firing the gun; the buttstock for shouldering and controlling the weapon; and the bolt for locking the action during discharge. One cycle of the action consists of locking the bolt on a cartridge, firing the cartridge, retracting the bolt to eject the spent case, and closing the bolt to feed a new cartridge. Actions are classified by the different means of operating the bolt: lever-action, bolt-action, falling-block, semiauto and automatic.
