[1] It is one of many squad automatic weapon-type firearms that have been developed from the Armalite AR-15 that use the Stoner bolt and carrier piston system.

[3] The CAR-15 weapons system consisted of the AR-15 and five variations, including the Colt Machine Gun and CAR-15 Heavy Assault Rifle.

[8] The 606 series was not successful as they were prone to rapid overheating, and the gas impingement system, together with the white nylon buffer, did not adapt effectively to sustained fire.

The Colt M16 HBAR was also included in the Squad Automatic Weapon (SAW) program, as requested by the U.S. Army’s Office of the Deputy Chief of Staff of Operations.

The weapon was essentially a modified M16A1 with a new square handguard to cover the enlarged straight gas tube and almost 1 inch thick heavy barrel to make the barrel less susceptible for overheating and hence increase the sustained or effective rate of fire capability, a carry handle on top of the handguard, with a hydraulic buffer assembly and the ability to fire from an open bolt.

Colt had also originally used the M60 machine gun bipod, but switched this to a proprietary design that was lighter for the subsequent Model 750.

The improved version featured all A2 parts and is essentially the same as the preceding variant externally except for the redesigned vertical foregrip, now of a ribbed straight cylindrical style.

[11] The Netherlands Marine Corps designate it as "LOAW" (licht ondersteunend automatisch wapen/light supporting automatic weapon) and the Danish military as "LSV M/04".

The lack of belt feed and quick barrel change options limits the C7 LSW and similar magazine fed light support weapon's rapid rates of fire.

New parts include a new retracting stock, ambidextrous controls, an Integrated Upper Receiver (IUR) with a free-floating barrel and RIS rails for mounting Laser Light Modules and other accessories.