Atchisson AA-12

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Atchisson AA-12
AA-12 automatic combat shotgun
TypeAutomatic combat shotgun
Place of originUnited States
Production history
DesignerMaxwell Atchisson (1930-2003); further developed by Military Police Systems, Inc.
DesignedOriginal design: 1972
MPS design: 2005
ManufacturerMaxwell Atchisson[1]
Mass5.2 kg less magazine. 7.3 kg with loaded 32-round drum (original version)
Length991 mm (Atchisson Assault Shotgun, 1972)
966 mm (AA-12, 2006)[2]
Barrel length457 mm

Cartridge12 Gauge
ActionAPI blowback[2]
Rate of fire300 rounds/min[3]
Muzzle velocity350 m/s (1,100 ft/s)
Effective firing range100 m (12 gauge slug)
Maximum firing range200 m (FRAG-12 ammunition)[4][3]
Feed system8 rounds in box magazine, 20 or 32 rounds in drum magazines
SightsIron sight, 2× zoom optical scope

The AA-12 (Auto Assault-12), originally designed and known as the Atchisson Assault Shotgun, is an automatic combat shotgun developed in 1972 by Maxwell Atchisson (however, the original development by Atchisson seems to have produced only a few guns at prototype-level, with the development that ultimately lead to the gun entering the market being done later by Military Police Systems, Inc.[5]). The most prominent feature is reduced recoil. The current 2005 version has been developed over 18 years since the patent was sold to Military Police Systems, Inc. The original design was the basis of several later weapons, including the USAS-12 combat shotgun. The shotgun fires in fully automatic mode only. However, the relatively low cyclic rate of fire of around 300 rounds per minute enables the shooter to fire semi-automatically de facto with brief trigger pulls. It is fed from either an 8-shell box magazine or a 20-shell drum magazine. The charging handle is located at the top of the gun and does not reciprocate during firing.


In 1987, Max Atchisson sold the rights of the AA-12 to Jerry Baber of Military Police Systems, Inc., Piney Flats, Tennessee.[6] MPS in turn developed the successor simply known as Auto Assault-12, which was redesigned over a period of 18 years with 188 changes and improvements to the original blueprint, modifications included changing the AA-12 from blowback- to gas-operated with a locked breech. "When the bolt flies back after firing to cycle another round, around 80% of what would normally be felt as recoil is absorbed by a proprietary gas system. A recoil spring grabs another 10%, leaving the final recoil a remarkable 10% of the normal recoil for a 12-gauge round—so you can point the AA-12 at a target and unload the full magazine without significant loss of accuracy".[7] MPS also teamed up with Action Manufacturing Company, and Special Cartridge Company to combine the gun with FRAG-12 High-Explosive ammunition into a multifunction weapon system.

The weapon was lightened to 4.76 kg (10.5 lb) and shortened to 966 mm (38.0 in) but retained the same barrel length. The CQB model has a 13-inch barrel, and is half a pound lighter than the regular model. Uncommon in other automatic shotguns, the AA-12 fires from an open bolt, a feature more commonly found in submachine guns, as well as heavy and squad-level machine guns. It uses 8-round box or 20-round drum magazines, as opposed to the original 5-round box magazine. Due to the abundant use of stainless steel and the designed clearance for fouling, MPS has stated that the weapon requires little to no cleaning or lubrication.[8] The designer states that cleaning is required after 10,000 rounds.[9] A rail system is also available for modern sighting options.[10] Because of an open bolt design, the AA-12 can reportedly operate after being submerged in water.[11]


The AA-12 is capable of firing various types of 12-gauge ammunition such as buckshot and slugs.


By 2004, ten firing models of the AA-12 had been produced [12] and were demonstrated to the United States Marine Corps, who did not adopt the weapon.[13]

The HAMMER unmanned defense system by More Industries proposed to use dual-mounted AA-12s on the H2X-40 turret.[14] Neural Robotics also wanted to mount the weapon on their AutoCopter unmanned aerial vehicle.[15][16]

See also[edit]


  1. ^ Johnson, Robert (2011-04-29). "10 Incredible Weapons That Only America Has". Business Insider. Retrieved 2021-03-08.
  2. ^ a b Maxim Popenker. "Modern Firearms – Atchisson AA-12". Retrieved April 5, 2012.
  3. ^ a b "Auto Assault-12 (AA-12) Full-Auto Machine Shotgun/FRAG-12 High-Explosive Round Combo/Weapon System!". Retrieved 2020-10-21.
  4. ^ "FRAG-12 Shotgun Ammunition Fact Sheet" (PDF). Defense Review. 2005-03-11. Retrieved 2021-03-08.
  5. ^ Pike, Travis (2021-07-10). "The AA-12: The Full Auto Shotgun From The Future". SOFREP. Retrieved 2023-04-09.
  6. ^ Moore, Jacob; Ruble, Drew (July–August 2009). "The Automatic Warrior". BusinessTN. Archived from the original on 2009-07-18.
  7. ^ "AA-12 combat shotgun". New Atlas. 2009-04-03. Retrieved 2021-03-08.
  8. ^ "Military Assault Shotgun". Guns, Hunting, Shooting at The Old Deer Hunters. August 11, 2010. Archived from the original on July 23, 2011. Retrieved October 27, 2018. During a Blackwater shoot, 5000 rounds were fired through a single weapon without cleaning or a drop of Lube.
  9. ^ Bartocci, Christopher R. (2014-05-16). "Made in the USA: The AA12 Shotgun by Christopher R. Bartocci". Archived from the original on 2021-11-07. Retrieved 2019-09-02.
  10. ^ "The AA-12: The Full Auto Shotgun From The Future". SOFREP. Retrieved 2022-05-14.
  11. ^ "AA-12 Fully Automatic Shotgun!!! - YouTube". Retrieved 2022-05-14.
  12. ^ Ratliff, Evan (2009-02-23). "Shoot! An Appalachian gunsmith's robot army". The New Yorker. Retrieved 2020-10-20.
  13. ^ Metesh, Logan (29 January 2019). "The AA-12 Automatic Shotgun". High Caliber History. Retrieved 2020-10-20.
  14. ^ Crane+, David. "HAMMER Remotely-Operated Weapons System for Robotic and Manned Vehicles". (DR): An online tactical technology and military defense technology magazine with particular focus on the latest and greatest tactical firearms news (tactical gun news), tactical gear news and tactical shooting news. Retrieved 2019-09-12.
  15. ^ Blass, Evan (1 March 2006). "Neural Robotics Incorporated equips AutoCopter with 12-gauge shotgun". Retrieved 2 September 2011.
  16. ^ "Remote Control Helicopter With Full-Auto Shotgun". 10 January 2008. Archived from the original on 2011-09-02. Retrieved 2 September 2011.