Guns sticker size 420 X 107 AR-15 (for Armalite model 15, often mistaken for Automatic Rifle or Assault Rifle) is the common name for the widely-owned semi-automatic rifle which soon afterwards became the fully automatic M16 and M4 Carbine assault rifles, which are currently in use by the United States military. AR-15 was the original name for what became the militarily designated M16, the assault rifle first used by the U.S. in the Vietnam War. The name AR-15 is now used almost exclusively to refer to the semi-automatic(commercially available)civilian version(s) of the M16 and M4 assault rifles.

All standard AR-15 rifles accept detachable magazines of widely varying capacities, and have a pistol grip that protrudes beneath the stock. AR-15 rifles are highly configurable and customizable, and are commonly fitted with several accessories, including bipods, bayonet lugs, folding or collapsing butt stocks, threaded barrels for the attachment of a flash suppressor or other accessories, and a Picatinny rail in place of the fore grip for the attachment of vertical grips, flashlights, laser sights, telescopic sights, and other accessories.