Advanced Combat Rifle
Encyclopedia
The Advanced Combat Rifle (ACR) was a United States Army
program to find a replacement for the M16 assault rifle
. The program's total cost is 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
.
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.
, 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 .42 round, eventually three in a .338 round.
Phase III began in August 1989, when AAI, Colt, HK, and Steyr entered weapon testing. Although all the designs worked well, none managed to meet or even approach the 100% improvement over the M16A2 that the program demanded. In 1986/7, the United States Army Infantry School
had published a report asserting that the rifle, as a weapon, had already reached its peak, and the only way to really improve matters was to use an exploding warhead. This led to the ending of the ACR program in April 1990, and led the way to the Objective Individual Combat Weapon program. The ACR program was preceded by older programs such as the Special Purpose Individual Weapon
.
entered the latest variant of their long line of experimental fléchette rifles. Their entry used a standard 5.56 x 45 mm cartridge case firing a 1.6 x 41.27 mm fléchette of 0.66 grams at 1402 m/s. One of the biggest complaints about their earlier efforts was the loud muzzle blast, a problem that is hard to avoid with a sabotted round. As a result, AAI added a flash hider/sound suppressor that reduced the muzzle blast to just louder than an M16A2. While the standard 5.56 x 45 mm case was used, the rifle was not safe to fire using standard ammunition due to the design of the gas system. A special magazine was used to prevent soldiers loading standard 5.56 mm NATO ammunition into the magazine, but rounds could still be chambered by hand. The weapon was limited to three-round bursts despite the fact that one of the main reasons for using a fléchette is its low recoil. This particular design was less complex than some of their earlier models, which could switch between fléchette ammunition for rapid fire and standard 5.56 NATO rounds for long-range semi-automatic fire.
G11
series used caseless ammunition
where the propellant was molded onto the bullet itself, making the round smaller and much lighter. The new K2 version used in the ACR tests held 45 rounds in a single long magazine lying along the top of the barrel, leading to a distinctive and somewhat blocky appearance.
, another fléchette-firing weapon. The Steyr differed from the AAI in the details of the round, which used a plastic shell casing to reduce weight. The firing mechanism was quite complex as a result, moving the entire chamber as opposed to just the bolt. When fired, the chamber would move down where a new round would be pushed in from the rear, forcing the spent cartridge case forward out of the chamber where it would drop out through an ejection port behind the pistol grip. The chamber would then move back into firing position on a spring, where it would lock in front of a fixed breechblock. On firing, the sabot traveled down the barrel with the fléchette and was quickly "stripped" off upon exit. This was found to present a hazard in combat, where the sabots could hit other soldiers or bounce off the ground when being fired prone. Like the AAI weapon, the Steyr was limited to three round bursts.
One of the more traditional of the ACR prototypes was the Colt ACR
, which was a highly modified version of the existing M16A2. Modifications were the addition of a new optical sighting system, a hydraulic buffer to smooth out recoil during automatic fire, and a collapsing butt stock similar to the one already in use on the carbine versions of the M16. The key design change was the use of "duplex rounds", a single cartridge with two smaller bullets in it. Olin Corporation produced three different rounds for testing, the first consisting of two tungsten
projectiles in a long-necked case, the second used a standard-length case with two 27 grain (1.75 g) 0.158-inch (4 mm) tungsten projectiles, and the final entry was another standard-length case with two 0.224-inch (5.69 mm) projectiles, one 35 grains, (2.27 g) the other 33 (2.14 g). The latter was eventually selected for submission to the ACR trials. The basic idea of the duplex load is to increase the amount of projectiles fired, which is the primary determinant of battlefield casualties. However, they significantly reduced accuracy, requiring the user to also carry traditional ammunition for long-range shots.
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...
program to find a replacement for the M16 assault rifle
Assault rifle
An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...
. The program's total cost is approximately US$
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
300 million. Phase I of the program started in February 1986 when development contracts were placed with six companies: AAI Corporation
AAI Corporation
AAI Corporation is an aerospace and defense development and manufacturing firm in Hunt Valley, Maryland, USA. It is formerly a wholly owned subsidiary of United Industrial Corporation, AAI was acquired by Textron in 2007 and currently is an operating unit of Textron Systems Corporation...
, Ares Incorporated
Ares Incorporated
ARES Incorporated is weapons manufacturer co-founded by Eugene Stoner in 1971. The company is based in Port Clinton, Ohio, and produces fire control systems, turret systems, small arms, automatic cannons and industrial machinery....
, Colt's Manufacturing Company
Colt's Manufacturing Company
Colt's Manufacturing Company is a United States firearms manufacturer, whose first predecessor corporation was founded in 1836 by Sam Colt. Colt is best known for the engineering, production, and marketing of firearms over the later half of the 19th and the 20th century...
, Heckler & Koch
Heckler & Koch
Heckler & Koch GmbH is a German defense manufacturing company that produces various small arms. Some of their products include the SA80, MP5 submachine gun, G3 automatic rifle, the G36 assault rifle, the HK 416, the MP7 personal defense weapon, the USP series of handguns, and the high-precision...
(H&K), McDonnell Douglas Helicopter Systems
MD Helicopters
MD Helicopters, Inc. is an aerospace company that produces helicopters primarily for commercial use. Coverage here includes the company's tenure as McDonnell Douglas Helicopter Systems, a subsidiary of McDonnell Douglas.-Background:...
(MDHS), and Steyr Mannlicher
Steyr Mannlicher
Steyr Mannlicher is a firearms manufacturer based in the city of Steyr, Austria. Originally a part of the Steyr-Daimler-Puch manufacturing conglomerate, it became independent when the conglomerate was broken in 1990.-History:...
.
Phase I and II
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
Eugene Stoner
Eugene Morrison Stoner is the man most associated with the design of the AR-15, which was adopted by the US military as the M16...
’s Ares Incorporated
Ares Incorporated
ARES Incorporated is weapons manufacturer co-founded by Eugene Stoner in 1971. The company is based in Port Clinton, Ohio, and produces fire control systems, turret systems, small arms, automatic cannons and industrial machinery....
also entered their Advanced Individual Weapon System (AIWS), which used a 5mm tracer
Tracer ammunition
Tracer ammunition are bullets that are built with a small pyrotechnic charge in their base. Ignited by the burning powder, the phosphorus tail burns very brightly, making the projectile visible to the naked eye...
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.
MDHS
McDonnell Douglas Helicopter Systems, originally Hughes HelicoptersHughes Helicopters
Hughes Helicopters was a major manufacturer of military and civil helicopters from the 1950s to the 1980s.The company began in 1947, as a unit of Hughes Aircraft, then was part of the Hughes Tool Company after 1955. It became the Hughes Helicopter Division, Summa Corporation in 1972, and was...
, 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 .42 round, eventually three in a .338 round.
Phase III
United States Army Infantry School
The United States Army Infantry School is located in Fort Benning, Georgia. It is made up of the following components:*192d Infantry Brigade...
had published a report asserting that the rifle, as a weapon, had already reached its peak, and the only way to really improve matters was to use an exploding warhead. This led to the ending of the ACR program in April 1990, and led the way to the Objective Individual Combat Weapon program. The ACR program was preceded by older programs such as the Special Purpose Individual Weapon
Special Purpose Individual Weapon
The Special Purpose Individual Weapon was a long-running United States Army program to develop, in part, a workable flechette-based "rifle", though other concepts were also involved...
.
AAI
AAI CorporationAAI Corporation
AAI Corporation is an aerospace and defense development and manufacturing firm in Hunt Valley, Maryland, USA. It is formerly a wholly owned subsidiary of United Industrial Corporation, AAI was acquired by Textron in 2007 and currently is an operating unit of Textron Systems Corporation...
entered the latest variant of their long line of experimental fléchette rifles. Their entry used a standard 5.56 x 45 mm cartridge case firing a 1.6 x 41.27 mm fléchette of 0.66 grams at 1402 m/s. One of the biggest complaints about their earlier efforts was the loud muzzle blast, a problem that is hard to avoid with a sabotted round. As a result, AAI added a flash hider/sound suppressor that reduced the muzzle blast to just louder than an M16A2. While the standard 5.56 x 45 mm case was used, the rifle was not safe to fire using standard ammunition due to the design of the gas system. A special magazine was used to prevent soldiers loading standard 5.56 mm NATO ammunition into the magazine, but rounds could still be chambered by hand. The weapon was limited to three-round bursts despite the fact that one of the main reasons for using a fléchette is its low recoil. This particular design was less complex than some of their earlier models, which could switch between fléchette ammunition for rapid fire and standard 5.56 NATO rounds for long-range semi-automatic fire.
H&K
The Heckler & KochHeckler & Koch
Heckler & Koch GmbH is a German defense manufacturing company that produces various small arms. Some of their products include the SA80, MP5 submachine gun, G3 automatic rifle, the G36 assault rifle, the HK 416, the MP7 personal defense weapon, the USP series of handguns, and the high-precision...
G11
Heckler & Koch G11
The Heckler & Koch G11 is a non-production prototype assault rifle developed during the late 1960s, 1970s and 1980s by Gesellschaft für Hülsenlose Gewehrsysteme , a conglomeration of companies headed by firearm manufacturer Heckler & Koch , Dynamit Nobel The Heckler & Koch G11 is a non-production...
series used caseless ammunition
Caseless ammunition
Caseless ammunition is a type of small arms ammunition that eliminates the cartridge case that typically holds the primer, propellant, and projectile together as a unit...
where the propellant was molded onto the bullet itself, making the round smaller and much lighter. The new K2 version used in the ACR tests held 45 rounds in a single long magazine lying along the top of the barrel, leading to a distinctive and somewhat blocky appearance.
Steyr
The last entry submitted was the Steyr ACRSteyr ACR
The Steyr ACR was a prototype flechette-firing assault rifle built for the US Army's Advanced Combat Rifle program of 1989/90. Although the Steyr design proved effective, as did most of the weapons submitted, the entire ACR program ended with none of the entrants achieving performance 100% better...
, another fléchette-firing weapon. The Steyr differed from the AAI in the details of the round, which used a plastic shell casing to reduce weight. The firing mechanism was quite complex as a result, moving the entire chamber as opposed to just the bolt. When fired, the chamber would move down where a new round would be pushed in from the rear, forcing the spent cartridge case forward out of the chamber where it would drop out through an ejection port behind the pistol grip. The chamber would then move back into firing position on a spring, where it would lock in front of a fixed breechblock. On firing, the sabot traveled down the barrel with the fléchette and was quickly "stripped" off upon exit. This was found to present a hazard in combat, where the sabots could hit other soldiers or bounce off the ground when being fired prone. Like the AAI weapon, the Steyr was limited to three round bursts.
Colt
Colt ACR
The Colt ACR was Colt's entry in the U.S. DoD Advanced Combat Rifle program, which concluded with the result that none of the entrants achieved enough of an improvement over the M16 to be worth the cost....
, which was a highly modified version of the existing M16A2. Modifications were the addition of a new optical sighting system, a hydraulic buffer to smooth out recoil during automatic fire, and a collapsing butt stock similar to the one already in use on the carbine versions of the M16. The key design change was the use of "duplex rounds", a single cartridge with two smaller bullets in it. Olin Corporation produced three different rounds for testing, the first consisting of two tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
projectiles in a long-necked case, the second used a standard-length case with two 27 grain (1.75 g) 0.158-inch (4 mm) tungsten projectiles, and the final entry was another standard-length case with two 0.224-inch (5.69 mm) projectiles, one 35 grains, (2.27 g) the other 33 (2.14 g). The latter was eventually selected for submission to the ACR trials. The basic idea of the duplex load is to increase the amount of projectiles fired, which is the primary determinant of battlefield casualties. However, they significantly reduced accuracy, requiring the user to also carry traditional ammunition for long-range shots.
See also
- Project AbakanProject AbakanProject Abakan was a Russian advanced assault rifle programme in rival to the US Advanced Combat Rifle that took place between 1980 to 1994.-History:The 1960s ushered a new generation of assault rifles with the introduction of smaller calibers. U.S...
— Similar programme to the ACR - List of individual weapons of the U.S. Armed Forces
- Polymer-cased ammunitionPolymer-cased ammunition-Overview:A plastic cylinder makes up the body of the cartridge. Starting from the back of the interior of the cartridge: The primer material. A priming method for rimfire cartridges is disclosed in which a propellant solution is disposed adjacent a centrifugally located primer material in a...
- XM8
External links
- Advanced Combat Rifles - detailed article on ACR's