A bayonet lug is a metal fitting on the barrel or muzzle of a firearm that provides a mounting point for a bayonet.

A firearm feed system where ammunition is stored in a separate container (magazine) that can be removed and replaced, enabling rapid reloading.

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

A pistol feature allowing it to fire grenades or projectile rounds.

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

A mounting system for attaching optical sights to rifles.

Select fire is a fire selector mechanism on a firearm that lets the shooter choose the firing mode, such as semi‑automatic, burst, or fully automatic.

A pistol barrel with external helical grooves allowing the attachment of a suppressor or other muzzle devices.