Colt CAR-15

The Colt CAR-15 is a family of carbines and submachine guns derived from the M16, marketed by Colt in the 1960s and early 1970s. The name is chiefly associated with the short-barrelled Colt Commando, adopted by the US Army as the XM177 series and by the US Air Force as the GAU-5, which saw extensive use with special operations units in Vietnam. Today "CAR-15" is used generically for all pre-M4 carbine-length variants.

Colt bought the rights to the AR-10 and AR-15 from ArmaLite in late 1959. The first Army and Air Force M16 contract followed in November 1963. The CAR-15 programme began in earnest in 1964 and was marketed from May 1965 as a modular weapon system of five variants: a submachine gun, a carbine, a heavy-barrelled squad automatic weapon, a belt-fed machine gun and a survival rifle, plus a 40 mm grenade launcher. Only the submachine gun drew US Army interest. The Model 606 heavy assault rifle was made in 100 to 150 examples for the 1965 SAWS evaluation, the belt-fed M2 and the Model 605 carbine remained prototypes, and about ten Model 608 survival rifles were built. Colt soon abandoned the family concept.

The Model 607 submachine gun was tested by Navy SEALs as early as 1964 and issued from 1965 in about 50 examples, mostly to SEALs, Army Special Forces and some K-9 units. It introduced the first retractable stock, 660 mm (26 in) long collapsed, but never entered production. Muzzle problems led Colt to fit an 89 mm (3.5 in) moderator in September 1966, then a 108 mm (4.25 in) six-slot moderator that became standard on the submachine gun and the Commando; fouling and tracer yaw persisted. The Colt Commando, introduced in 1966, replaced the 607 with a two-position telescoping aluminium stock and round handguards made of two identical halves. It was offered as the Model 609 with forward assist and the Model 610 without; the Model 610 corresponds to the XM177 and to the Air Force GAU-5/A; the ATF regards the moderator as a sound suppressor.

On 28 June 1966 the Army bought 2,815 Model 609 Commandos as the Submachine Gun, 5.56 mm, XM177E1, with a 254 mm (10 in) barrel and the 110 mm (4.2 in) moderator. Most shipped with 20-round rather than the intended 30-round magazines, which only became available in November 1967. In 1967 the barrel was lengthened to 292 mm (11.5 in), with a chrome-plated chamber and a boss on the moderator for the XM148 grenade launcher and rifle grenades, as the Model 629 with forward assist and Model 649 without. In April 1967 the Army bought 510 Model 629s for MACV-SOG as the XM177E2, delivered by the end of September 1967, and the Air Force adopted its own version as the GAU-5A/A. Colt's proposals for a six-month, $400,000 ballistic study and a 29-month, $635,000 development programme were both declined, and Commando production ended in 1970.

After Vietnam the Air Force refitted its GAU-5s with 14.5 in barrels as the GUU-5/P, a weapon also used by the British SAS during the Falklands War. Colt's later 14.5 in carbines included the Model 653 M16A1 carbine, the only one bought in significant numbers by the US military, the Model 723 used by Delta Force, the Model 725 adopted by the Canadian Forces as the C8 from 1983, and ultimately the M4, requested as the XM4 in 1984 and adopted in 1994. The M4 Commando, with an 11.5 in barrel, exists as the Model 733, the flattop Model 933 (semi-automatic and automatic) and Model 935 (semi-automatic and burst); it has served with Marine Corps Force Reconnaissance and US Army Special Operations Command, while Navy SEALs use the 10.3 in Mk 18 Mod 0. In 2019 the Air Force introduced the GAU-5A Aircrew Self Defense Weapon, built at the USAF Gunsmith Shop at Joint Base San Antonio-Lackland to fit the ejection-seat survival kits of the A-10, B-1, B-2, B-52, F-15C/E, F-16 and F-22; 2,137 are planned.