CAR-15 based on M16
The Colt Automatic Rifle-15 or CAR-15 is a family of M16 rifle–based firearms marketed by Colt in the 1960s and early 1970s. However, the term "CAR-15" is most commonly associated with the Colt Commando (AKA: XM177); these select-fire carbines have ultrashort 10.5-inch (270 mm) and 11.5-inch (290 mm) barrels with over-sized flash suppressors.
The CAR-15 name was an attempt to re-associate the AR-15 name with Colt, since the AR initially stood for ArmaLite, the original manufacturer of the ArmaLite AR-15. Colt later abandoned the CAR-15 concept, but continued to make carbine variations, using the "M16" brand for select-fire models and the "Colt AR-15" brand for semi-automatic models. However, in present usage, "CAR-15" is the generic name for all carbine-length variants made before the M4 carbine.Colt Automatic Rifle-15 family
CAR-15 Rifle (AKA: M16 rifle)
The Model 603 CAR-15 Rifle, adopted initially by the United States Army as the XM16E1 and then later as the M16A1, and the Model 604 CAR-15 Rifle, adopted by the United States Air Force as the M16, formed the core of the CAR-15 family. However, the United States military had already committed to purchases before Colt created the concept of the CAR-15 weapons system. The principal difference between the Model 603 and Model 604 is that the former has a forward assist, allowing a user to manually close a stuck bolt.