Differences between the Colt M4 and the Colt 6920 assault rifles include barrel length and weight, as noted by Colt's Manufacturing Company. The Colt M4 has a 14.5-inch barrel length, while the Colt 6920 has a barrel length of 16.1 inches. The Colt M4 weighs 6 pounds 11 ounces, and the Colt 6920 weighs 6 pounds 9 ounces.
Other differences between the assault rifles are the retracted and extended lengths, lists Colt's Manufacturing Company. The Colt M4 retracted length is 29.8 inches, and its extended length is 33 inches. The Colt 6920 has a 32-inch retracted length and a 35.5-inch extended length.
Designed as a lightweight weapon with potent firepower, the Colt M4 includes the R0920 Safe-Semi-Burst and R0921 Safe-Semi-Auto models used by the U.S. military, according to Colt's Manufacturing Company. The R0977 Safe-Semi-Auto and R0979 Safe-Semi-Burst are international models. Available in five models, the Colt 6920 includes a locking bolt and direct gas systems, as well as a flip-up rear sight that is adjustable for windage.
Assault weapons are semiautomatic and allow their users to quickly spray multiple bullets at a target while maintaining control of the weapon, according to Law Center to Prevent Gun Violence. The site points out that seven states and the District of Columbia ban assault weapons.