Firearm action

A firearm action is the mechanism that loads, locks, fires, extracts, and ejects cartridges. Its design determines how a firearm cycles between shots and how it is operated.

Bolt-action firearm: A firearm whose manually operated bolt locks the breech and cycles cartridges. Its handle-operated cycle separates chambering, firing, extraction, and ejection into distinct steps.
Breech mechanism: The assembly that closes the rear of a firearm’s chamber and supports firing. The action’s locking components secure this boundary against firing pressure.
Manual action firearm: A firearm whose operator manually cycles the mechanism between shots. Manual actions contrast with systems that use firing energy to cycle automatically.
Matchlock: An early firearm ignition system that used a mechanically held, smoldering match to ignite powder. It illustrates an early mechanism for firing, before modern repeating actions.
Firearm reliability: The ability of a firearm to function consistently under specified conditions. Action complexity, fouling, and ammunition sensitivity can affect reliable cycling.
Lever-action firearm: A firearm that uses a lever, usually surrounding the trigger guard, to cycle its action. The lever moves the breech mechanism and typically operates the magazine feed.
Chamber (firearms): The part of a firearm that holds a cartridge in position for firing. Actions move cartridges into and out of this location.
Automatic firearm: A firearm that continues firing while its trigger is held and ammunition remains available. Its action can repeat firing without a separate trigger pull for each shot.
Flintlock: A firearm ignition mechanism that struck flint against steel to produce sparks. Its trigger-operated lock is an influential predecessor to later firearm mechanisms.
Rate of fire: The number of shots a firearm can discharge in a given period. Automatic cycling and manual operation impose different limits on firing speed.

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