
Once the bolt is fully unlocked it begins its rearward movement along with the bolt carrier. As the bolt carrier moves toward the butt of the gun, the bolt cam pin, riding in a slot on the bolt carrier, forces the bolt to rotate and thus unlocks it from the barrel extension. Īt this point, the bolt is locked into the barrel extension by locking lugs, so the expanding gas forces the bolt carrier backward a short distance. Here, the gas tube protrudes into a "gas key" (bolt carrier key), which accepts the gas and funnels it into the bolt carrier. The gas expands into the port and down a gas tube, located above the barrel that runs from the front sight base into the AR-15's upper receiver. Gas is tapped from the barrel as the bullet moves past a gas port located above the rifle's front sight base. Designer Eugene Stoner did not consider the AR-15 to be a conventional direct impingement mechanism, but that is how it came to be characterized. This mechanism is often called " direct gas impingement" (DGI), although it differs from prior gas systems. The bolt carrier acts as a movable cylinder and the bolt itself acts as a stationary piston.

Patent 2,951,424 describes the cycling mechanism used in the original AR-15. Over the decades, Colt has made many different types of AR-15 rifle and carbine models, including the AR-15, AR-15A2, AR-15A3, AR-15A4, and many other models.Īlthough the sale of new AR-15s was banned by the Federal Assault Weapons Ban from 1994 to 2004, Colt and others continued to sell legally compliant versions during that period. 223 Remington, with a 20-inch barrel and issued with 5-round magazines. The first mass production version was the Colt AR-15 Sporter, in. Colt started selling the semi-automatic version of the M16 rifle as the Colt AR-15 in 1964. This example is fitted with an early waffle-patterned 20-round magazine.ĭue to financial problems, and limitations in terms of manpower and production capacity, ArmaLite sold the ArmaLite Rifle-15, abbreviated AR-15 design and the AR-15 trademark along with the ArmaLite AR-10 to Colt's Manufacturing Company in 1959. Colt's Manufacturing Company currently uses the AR-15 trademark for its line of semi-automatic AR-15 rifles.įor more a more detailed list of AR-15 models, see List of Colt AR-15 & M16 rifle variants#Colt civilian models.ġ973 Colt AR-15 SP1 rifle with "slab side" lower receiver (lacking raised boss around magazine release button) and original Colt 20-round box magazineĪ Colt AR-15 on display at the National Firearms Museum. It is a semi-automatic version of the United States military M16 rifle that is marketed to civilian and law-enforcement customers. It was designed to be manufactured with extensive use of aluminum alloys and synthetic materials.

The Colt AR-15 is a lightweight, 5.56×45mm, magazine-fed, gas-operated semi-automatic rifle.
