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

Firearm mechanism where double action (DA) requires a long trigger pull to cock and release the hammer, while single action (SA) requires only a short pull to release a pre-cocked hammer.

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