One CMG-1 used direct impingement and shared the bolt, gas tube, and other operating parts of the M16.
Colt offered the CMG-1 in four different versions: bipod-mounted, tripod-mounted, vehicle-mounted, or fixed mount.
bipod-mounted version was marketed as a light machine gun for use by assault troops.
The CMG-2 abandoned any commonality with the M16 and was only available as a bipod-mounted full-automatic-fire-only light machine gun with a vertical foregrip.
The extractor was machined into the bolt and ejected spent rounds down through the vestigial magazine well.
The operator charged the CMG-2 by unlocking the pistol grip and then sliding it forward and back to chamber a round from the belt and cock the weapon.
It was fed from a disintegrating metal belt using Stoner's proprietary S-63 BRW links.
Belted ammo was contained in a 150-round Stoner green or black plastic drum that mounted on the left-hand side of the weapon.