- That part of a modern revolver that holds cartridges in separate chambers radially around a central hingepin. The cylinder revolves as the handgun is cocked, bringing each successive cartridge into position, and locked into alignment with the barrel for firing.
- A rotating cartridge holder in a revolver. The cartridges are held in the chambers and the cylinder turns, either to the left or to the right depending on the gun maker's design, as the hammer is cocked.
- A shotgun barrel with no choke constriction at the muzzle.