The Auto-Assault 12 (AA-12), originally designed and known as the Atchisson Assault Shotgun, is a shotgun developed in 1972 by Maxwell Atchisson. 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.
In 1987, Max Atchisson sold the rights of the AA-12 to Jerry Baber of Military Police Systems, Inc., Piney Flats, Tennessee. 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.
The AA-12 weighs 11 pounds, and is 99 centimetres long. It has a barrel length of 45 centimetres, with a rate of fire of 300 rounds per minute. It has an effective firing range of 100 metres, and a maximum firing range of 200. The AA-12 can hold 8 rounds in a box magazine, or 20 to 32 in a drum.