That part or apparatus of a firearm by which the charge is exploded; as, a matchlock, flintlock, percussion lock, etc.

Traditionally referred to the firing mechanism of muzzle-loading firearms as in "lock, stock, and barrel." In modern firearms, the term can refer to the firing mechanism and breech-sealing assembly or to the action of "locking" or securing the bolt of a firearm prior to firing.

A general term referring to the total firing mechanism in a firearm. Range command sometimes used to indicate engagement of a manual safety (“Lock you firearms”). An externally applied device intended to help secure a firearm.

The firing mechanism of a muzzle loading firearm.

The lock of a firearm is the system used to ignite the propellant. Types of lock include matchlock, wheellock, flintlock, modern percussion, and experimental electronic types. A complete firearm often consists of lock, stock, and barrel.