A cylindrical ammunition container, typically mounted on a firearm, that holds cartridges in a spiral arrangement for feeding into the chamber.

Firearm action type where expanding gas from a fired cartridge cycles the mechanism, typically via a piston or direct impingement.

Uses high-pressure gas to cycle the action, rather than recoil energy.

Adjustable metal aiming devices on firearms, consisting of a front post and rear notch, used without magnification.