The Colt ACR featured a flat top rail system that could mount either an iron sight on a raised handle or the ELCAN sight, shown here, a feature later used extensively on M4 Carbines and M16A4 rifles. (NATIONAL INFANTRY MUSEUM)
In use, the M231 has a generally poor reputation. The weapon fires full-auto only, with a cyclic rate of about 1,200 rounds per minute. The M231 does not have any sights. The soldiers were to aim using periscopes mounted in the Bradley and spot their fire by firing only tracer rounds from standard 30-round M16 magazines. The difficulty in aiming, combined with the extremely high rate of fire, meant that the magazines would be emptied before the shooter could get rounds on the target. Later modifications to the Bradley covered up the side firing ports with additional armor and now only the two firing ports on the rear hatch remain. The original design included a simple wire stock so the M231 could be dismounted from the vehicle and used on foot. This stock was dropped from production models and Army procedures discouraged the use of the M231 outside of the vehicle. Ironically, it is in this role that the M231 has probably seen the most use. Photographs from Iraq show U.S. soldiers using the M231 as a backup weapon in vehicle turrets. They have also been carried by officers and armored crewman who normally are only armed with a handgun. Since modern 5.56mm NATO ammunition is optimized for 1-in-7-inch twist 86
American Shooting Journal // January 2018
A closer view of the Colt ACR reveals the M16A2 heritage, including the forward assist. Note the enlarged ambidextrous selector switch. (NATIONAL INFANTRY MUSEUM)
barrels, and not for the older twist of the M231, the weapon is effective at only very short ranges. When you consider the lack of appropriate ammo, the absence of sights, and the difficulty controlling a weapon with such a high rate of fire, you understand how desperate a soldier has to be to use a M231. THE COLT ADVANCED COMBAT RIFLE (ACR) The Colt Advanced Combat Rifle was part of the Army’s search for a weapon to improve the average soldier’s ability to hit his enemy in combat. The specifications for the
The fire controls of the Colt 231 Firing Port Weapon. (ROB REED)
rifle called for a 100 percent hit probability increase over the thencurrent-issue M16A2 rifle. The program started in the mid-’80s with six manufacturers submitting prototypes, and by 1989 only four remained. These included