In firearms terminology, an action is the mechanism that handles the ammunition or the method by which that mechanism works. Breech-loading weapons have actions, actions are not present on muzzleloaders. The mechanism that fires a muzzle-loader is called the lock, actions can be categorized in several ways, including single action versus double action, break action versus bolt action, and others. The term action can also short, long, and magnum if it is in reference to the length of the rifle’s receiver. The short action rifle usually can accommodate a cartridge length of 2.8 in or smaller, the long action rifle can accommodate a cartridge of 3.34 in, and the magnum action rifle can accommodate cartridges of 3.6 in, or longer in length. Manual operation is a term describing any type of firearm action that is loaded one shot at a time by the user rather than automatically. For example, break action is a form of operation using a simple hinge mechanism that is manually unlatched by the operator. These are actions wherein the breechblock lowers or drops into the receiver to open the breech, there are two principal types of dropping block, the tilting block and the falling block. In a tilting or pivoting block action, the breechblock is hinged on a pin mounted at the rear, when the lever is operated, the block tilts down and forward, exposing the chamber. The best-known pivoting block designs are the Peabody, the Peabody–Martini, the original Peabody rifles, manufactured by the Providence Tool Company, used a manually cocked side-hammer. The 1871 Martini–Henry which replaced the trapdoor Snider–Enfield was the standard British Army rifle of the later Victorian era, charles H. Ballards self-cocking tilting-block action was produced by the Marlin Firearms Company from 1875, and earned a superlative reputation among long-range Creedmoor target shooters. Surviving Marlin Ballards are today highly prized by collectors, especially those mounted in the elaborate Swiss-style Schützen stocks of the day. A falling-block action is a firearm action in which a solid metal breechblock slides vertically in grooves cut into the breech of the weapon. Examples of firearms using the falling block action are the Sharps rifle, in a rolling block action the breechblock takes the form of a part-cylinder, with a pivot pin through its axis. The operator rotates or rolls the block to open and close the breech, it is a simple, rugged, a break action is a type of firearm where the barrel are hinged and can be broken open to expose the breech. The earliest metallic-cartridge breechloaders designed for military issue began as conversions of muzzle-loading rifle-muskets. The upper rear portion of the barrel was filed or milled away, an internal angled firing pin allowed the re-use of the rifles existing side-hammer. The Allin action made by Springfield Arsenal in the US hinged forward, france countered in 1866 with its superior Chassepot rifle, also a paper-cartridge bolt action
A view of the break-action of a typical double-barreled shotgun, with the action open and the extractor visible. The opening lever and the safety catch can also be clearly seen.
Ruger No. 1 single-shot falling-block rifle with action open