Carbon 15

The Carbon 15 is a family of lightweight, magazine-fed pistols, carbines, and rifles developed by defunct United States weapons manufacturer Professional Ordnance, with the design picked up after some time by current manufacturer Bushmaster Firearms.
Overview.
The Carbon 15 line of weapons are closely based on the Colt AR-15 design. They are distinguished by their carbon fiber construction, which provides an extremely lightweight frame. The Carbon 15 line are generally 5.56 mm (.223 caliber) weapons, however there are 9 mm versions of the Carbon 15 pistol and carbine.
Early in 2009 Bushmaster, the primary manufacturer of Carbon-15 pistols/rifles, began to include the dust cover and forward assist in their Carbon-15 M4 rifles.