Firearm configuration where the action and magazine are located behind the trigger, reducing overall length while maintaining barrel length.

A rotating cylindrical chamber that holds multiple cartridges and aligns each with the barrel for firing, as used in revolver-type pistols.

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.

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.