CMG-1

The Colt Machine Gun-1 or CMG-1 was an open bolt belt-fed machine gun that fired 5.56x45mm cartridges designed by Colt Manufacturing Company in 1965. Colt hastily developed the CMG-1 to complement the CAR-15, a Colt branding of the M16 rifle, so that Colt might offer both of them as an alternative to the Stoner 63 weapons system. It failed to achieve any sales, and was replaced by the Colt CMG-2, which also failed to achieve any sales.

Though marketed together with the CAR-15, the CMG-1 had few parts in common with it. One CMG-1 used direct impingement and shared the bolt, gas tube, and other operating parts of the M16. However, other CMG-1s used gas pistons. The CMG-1s also used the M16's pistol grip, front sight block, and flash hider. Similar to the Stoner 63, the CMG-1 could be fed from either side. The rate of fire was 650 rounds per minute. Only two or three CMG-1s were ever made. Colt made them with sheet-metal stamping.

Colt offered the CMG-1 in four different versions: bipod-mounted, tripod-mounted, vehicle-mounted, or fixed mount. The 11.5 lb. bipod-mounted version was marketed as a light machine gun for use by assault troops. It was the only version with a buttstock. The 12.5 lb. tripod-mounted version was considered a medium machine gun. The vehicle mounted version was a pintle-mounted machine gun for use by soldiers in land vehicles. The fixed mount version was fired by a solenoid allowing for remote operation so it could be mounted in a helicopter or other aircraft.

In 1967, Colt replaced the CMG-1 with the CMG-2. The CMG-2 abandoned any commonality with the M16 and was only available as a bipod-mounted light machine gun with a vertical foregrip. It was fed from a 150-round belt using S-63 link contained in a drum. The CMG-2 was gas-piston operated, but used an M16 bolt. The extractor was machined into the bolt. The CMG-2's barrel was detachable and had a handle, so an overheated barrel could be replaced in the field. The barrel had a 1:9 twist and was meant to fire an experimental 68 gr bullet, designed for longer ranges than the then-standard 55 gr M193 bullet. Unlike the M60 machine gun, then in use in the Vietnam War, an M2 bipod was mounted on the CMG-2's ventilated handguard. The most unusual feature was that a user charged the CMG-2 by unlocking the pistol grip, and then sliding it forward and back. Colt submitted a buttstock-less short-barreled CMG-2 to the Navy SEALs. The Navy classified the CMG-2 as the EX 27 Mod 0 machine gun but they ultimately chose the Stoner 63 MK23 Mod 0 Commando instead. The CMG-2 never left prototype phase and Colt ceased development in 1969.