The Colt Commando (also known as XM177 or GAU-5) is an American 5.56×45mm NATO assault rifle. It is essentially the shorter variant of the M16A1. Entered service in 1966, the weapon saw first use during the Vietnam War.
The term CAR-15 originally refers to any Colt-marketed AR-15, but it became associated with this military variant.
If you are seeing what appears to be an M4-like rifle in images that take place before the mid-1990s (i.e., during the Vietnam War), the protruding barrel length is notably shorter in comparison with the forearm, or if the gun lacks more recent tactical features like Picatinny rails, then it is the Colt Commando.
Outside a military or police context, use AR-15 (civilian-legal counterpart) instead. Since the details on the fire selector are not always shown or clearly depicted.
