Atchisson Assault Shotgun
| Atchisson assault shotgun | |
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| The Atchisson assault shotgun | |
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| Type | combat shotgun |
| Land of Origin | United States |
| Specifications | |
| Length | 991 mm (1972) 966 mm (2006) |
| Barrel length | 457 mm |
| Weight | 5.2 kg less magazine. 7.3 kg with loaded 20-round drum |
| Gauge | 12 gauge |
| Cartridge | 2 3/4" magnum shells |
| Action | selective fire, blowback operated (1972) selective fire, gas operated, locked breech (2006) |
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| Rate of Fire | 360 RPM, cyclic |
| Feed | 5/8 (1972/2006) rounds in box
20 or 32 rounds in drum magazines |
| Sights | rear diopter, post front |
| Service History | |
| In service | pending |
| Used by | United States? |
| Wars | none yet |
| Production History | |
| Designer | Maxwell Atchisson |
| Design Date | 1972 |
| Manufacturer | MPS |
| Unit Cost | not currently available |
| No. Built | unknown |
| Variants | Atchisson Assault CQB |
The Atchisson Assault Shotgun, also known as, Auto Assault-12 (AA-12) was a firearm first developed in 1972 by Maxwell Atchisson. It served as the basis of several later weapons, including the USAS-12 combat shotgun. The weapon could fire in semi automatic or fully automatic modes.
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[edit] Development history
American gun designer Maxwell Atchisson developed his first selective fire shotgun by 1972. This weapon was intended for close combat in environments like city streets or jungles. It was to provide tremendous short range firepower for troops during ambushes, room clearance operations and other such combat situations. First prototypes were rather simple in design and used certain components of existing weapons. These were also highly unusual in that Atchisson used most unusual (for shotgun) method of operation - simple blowback with advanced primer ignition. This shotgun fired from open bolt, and had rather heavy (1,4kg) bolt. Firing pin was movably built into bolt along with the internal pivot lever that caused the firing pin to extend and ignite the cartridge just prior to full bolt closure. To reduce peak recoil and cyclic rate of fire, Atchisson used extra-long recoil system, in which bolt after each shot recoils much further back than it is usually required to reload the weapon. Receiver of early Atchisson shotgun was made from steel tube, with attached M16-type buttstock and forearm. This shotgun also employed trigger group borrowed from Browning BAR-1918 automatic rifle, which allowed for selective semi-automatic of full-automatic fire from open bolt. Feeding was from detachable magazines, either 5-round boxes or 20-round drums. To provide necessary support for heavy drum magazines during recoil, gun was equipped with magazine support bracket that rested against pistol grip. Simple sights were of open type, with non-adjustable rear diopter and post front, both mounted on high bases.
During late 1970s and early 1980 Atchisson reworked his basic design from open bolt blowback action to more safe locked breech, gas operated action. This was done in the view of the use of more powerful, specially developed military shotgun ammunition, loaded with flechettes or heavy load of buckshot. This system employed the traditional gas chamber and piston, located above the barrel, and locking system that used single vertically sliding locking lug in the bolt head. Upon closure of the bolt, this lug was forced up to lock into the projection of the barrel. Upon discharge, gas piston forced the bolt carrier back, which, in turn, first lowered the locking lug to unlock the bolt, then carried the bolt back for reloading cycle. New weapon retained the long bolt travel, but had more conventional hammer-fired trigger unit, and it still fired from open bolt. The stock and receiver also were redesigned; now, receiver, shoulder stock and forearm were made as a single housing, assembled from two symmetrical units, left and right. This weapon also was selective fired, and used M16-style safety / fire selector on the left side of receiver, above pistol grip.
[edit] MPS version
In 1987, Max Atchisson sold the rights of AA-12 to Jerry Baber of Military Police Systems, Inc. The company 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. MPS also teamed up with Action Manufacturing Company, and Special Cartridge Company to combine the gun with FRAG-12 High-Explosive ammunition into a weapon system. In 2004, 10 firing models of the AA-12 were produced and demonstrated to United States Marine Corps.
This second generation design languished for almost two decades, but recently it has been picked up by Military Police System (MPS) Co of Tennessee, USA that offers the slightly modified AA-12 selective fired shotgun for authorized military and police users in USA. It is possible that AA-12 will be used in limited numbers by some US agencies, but so far we have no information on actual use of this awesome weapon, which traces its ancestry to late days of Vietnam war.
[edit] Changes
The weapon was shortened to 966mm but retained same barrel length as the original, and lightened to 4.76kg. The CQB model has 13-inch barrel length, and is half a pound lighter than the regular model. It uses 8-round box, 20-round drum, or 32-round drum magazines, as opposed to the original 5-round box magazine. It is designed to fire three different types of 3" 12 gauge shells: Buckshot, slug, or Frag-12 rounds. MPS has claimed that the weapon requires zero cleaning or lubrication.
[edit] Variants
- The Atchisson Assault CQB model comes with a 13 inch barrel length and is weighted a half pound lighter than the regular model.
[edit] Media Coverage
The MPS version was featured on the March 19, 2007 episode of Future Weapons.
