Advanced Combat Rifle

The Advanced Combat Rifle (ACR) was a United States Army program, started in 1986, to find a replacement for the M16 assault rifle. Under the stress of battle the average soldier with an M16 could guarantee hitting a target at 45 meters, but hit probability was reduced to one out of ten shots on target by 220 meters. Because of this, The ACR program was initiated in the late 1980s to create a weapon that could double the hit probability. The ACR program was preceded by older programs such as the Special Purpose Individual Weapon. The program ended in 1990 after an expenditure of approximately US$300 million.

Phase I of the program started in February 1986 when development contracts were placed with six companies: AAI Corporation, Ares Incorporated, Colt's Manufacturing Company, Heckler & Koch (H&K), McDonnell Douglas Helicopter Systems (MDHS), and Steyr Mannlicher.

Two weapons were cut from the list before Phase II started. The companies started an appeals process and were eventually re-instated, but too late to see testing before the ACR program ended.

Eugene Stoner’s Ares Incorporated also entered their Advanced Individual Weapon System (AIWS), which used a 5mm tracer round, but had to withdraw due to ongoing problems. The AIWS shared some features with the Steyr entry, notably the "rising chamber" action and "telescoped" cartridge.

McDonnell Douglas Helicopter Systems, originally Hughes Helicopters, planned to enter their design using a plastic-cased cartridge they called a chiclet due to its box-like profile. Their first loads used duplex or triplex loads of normal projectiles, but the recoil was too high, so these were replaced with fléchettes, first with five of them in a 11-millimetre (.42 in) round, eventually three in a 8.6-millimetre (.338 in) round.

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