Semi-automatic Rifle

A semi-automatic rifle is a type of rifle that fires a single bullet each time the trigger is pulled, automatically ejects the spent cartridge, chambers a fresh cartridge from its magazine, and is immediately ready to fire another shot. They may be operated by a number of mechanisms, all of which derive their power from the explosion of the powder in the cartridge that also fires the bullet. Historically, the self-loading design was the successor to the repeating rifle, which stored a number of cartridges within the weapon, but required manual action to load a fresh cartridge before each shot. Automatically loading the next round more easily allows for rapid fire. These rifles are also commonly known as self-loading rifles ('SLR') or auto-loading rifles.

A semi-automatic rifle is distinguished from a fully automatic rifle or machine gun in that it can only fire once each time the trigger is pulled. In some contexts, the term "automatic rifle" may refer to a semi-automatic/self-loading rifle, not a fully automatic rifle. The magazine in a semi-automatic rifle is usually of a box-type which protrudes underneath the receiver and feeds cartridges vertically into the action. These may be fixed (as with M1 Garand, in which case cartridges are loaded from the top of the weapon, with the bolt locked back). Most modern designs use a detachable magazine, which is removed for reloading. Some detachable-magazine rifles, such as the M14, can also be top-loaded. Some designs use a horizontal tubular magazine similar to lever-action and pump-action weapons, which may be located underneath the barrel or in the butt stock.