The ADCOR A-556 is an assault rifle based on the M16/M4 series. It is produced by the Adcor Defense Company and was one of the contenders in the US Army Individual Carbine Competition to replace the

M4 Carbine The M4 carbine (officially Carbine, Caliber 5.56 mm, M4) is a 5.56×45mm NATO, gas-operated, magazine-fed carbine developed in the United States during the 1980s. It is a shortened version of the M16A2 assault rifle. The M4 is extensively ...

History

In 2005, Adcor Defense was contracted by Colt to produce upper receivers for the

. Adcor was able to produce 1,000 uppers per day, compared to 450 uppers per day that Colt was able to manufacture. After years of production, Adcor Defense decided to improve upon the weapon. They claimed it was not a “new and improved” AR, but a patented revolutionary gas piston system with other key features that set it apart from all other M4-type rifles.

Testing

In early 2010, Adcor sent the ADCOR A-556 rifle to H.P. White Laboratory, known for small arms and ammunition research, development, and testing, to test the reliability of the design. Testing took place from March to April. 6,000 rounds were fired in 120 round cycles, and the guns were lubricated and allowed to cool after 600-round intervals. During the tests, no parts had to be replaced and there were no jams, stoppages, or malfunctions of any kind. Following this, the A-556 was able to shoot a .88

MOA Moa are extinct giant flightless birds native to New Zealand. The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as Kale moa and Moa Samoa. Moa or MOA may also refe ...

group at 100 yards with 69-grain match ammo.

Production

On December 8, 2010, Adcor announced production of the A-556 rifle to the civilian market. On June 27, 2011, it was announced that the improved A-556 Elite variant would be available for sale to the public. In June 2012, a soldier was seen in Afghanistan with a A-556 upper receiver with a 10.5 inch barrel on an M4 lower receiver.

Individual Carbine Competition

On May 12, 2011, Adcor announced that its A-556 rifle had been entered in the

U.S. Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cl ...

Individual Carbine The Individual Carbine was a competition to select the planned successor to the M4 carbine in the United States Army. The U.S. Army conducted an open competition for a carbine to replace the M4. This competition was for the Army only—the Uni ...

competition. They say their design increases the reliability, accuracy, and lethality of the existing soldier weapon. "The A-556 combines a new piston system with an exclusive ejection port dust wiper with cover, an ambidextrous forward placing charging handle, and a new key-locked, highly rigid rail system." On May 4, 2012, the A-556 Elite version was selected into phase II of the competition. The Individual Carbine competition was cancelled before a winning weapon was chosen. On 17 July 2013, Adcor announced it would not protest the Army's decision to terminate the program, and would focus on delivering A-556 rifles to commercial customers. Test results made available to the company said the Army found the A-556 provided “outstanding” accuracy, even after firing thousands of rounds.

Design details

The cornerstone of the A-556 rifle design is the piston operating system. A gas-driven piston is incorporated into the upper half of the forward rail system and never touches the barrel. This makes the barrel free-floating, which increases accuracy. The operating rod is connected to the bolt carrier group and rides through a machined boss in the receiver rail system interface, keeping the bolt carrier in a linear plane as it operates. This eliminates carrier tilt. A spring-loaded dust shield mounted on the bolt carrier allows the bolt carrier to return to ready position. The port dust wiper moves into the ejection port opening flush of the upper receiver. A forward placed, foldable, non-reciprocating charging handle is mounted on the handguard, allowing the weapon to be charged or cleared while keeping it pointed toward a target. It is ambidextrous, being able to be removed without tools to either side of the gun. The A-556 has integrated

picatinny rail The Picatinny rail ( or ), or Pic rail for short, also known as a MIL-STD-1913 rail, 1913 rail or STANAG 2324 rail (cancelled), is a military standard rail interface system that provides a mounting platform for firearm accessories. It was ...

s for mounting accessories. The handguard has an M4 profile, so the charging handle is placed directly above the rail. Therefore, it needs a completely unobstructed space on the rail to charge the rifle, negating the usefulness of the rail on the side it is on. By contrast, on weapons like the

Adaptive Combat Rifle The Adaptive Combat Rifle (ACR) is a modular assault rifle designed by Magpul Industries of Austin, Texas, and known initially as the Masada. In late January 2008, Bushmaster Firearms International entered into a licensing agreement with Magpul ...

and the

FN SCAR The FN SCAR (Special Operations Forces Combat Assault Rifle) is a family of gas-operated short-stroke gas piston automatic rifles developed by Belgian manufacturer FN Herstal (FN) in 2004. It is constructed with modularity for the United State ...

, the charging handle is raised off the side rails, allowing things to be mounted.

Variants

ADCOR A-556 rifles come in barrel lengths of 10.5", 14.5", 16", 18", and 20".http://adcordefense.com/products/ - AdcorDefense.com

Users

*: Under evaluation and possible adoption by the Hellenic Armed Forces and manufacture under licence by EAS. *: Used by Special Task and Rescue (STAR).

References

External links

Adcor Defense website
{{ArmaLite AR-10 derivatives ArmaLite AR-10 derivatives AR-15 style rifles 5.56 mm assault rifles