JR Potts, AUS 173d AB (Updated: 9/23/2016):
As a new type of assault combat shotgun, the AA-12 itself is intended to be a lethal offensive weapon in the same vein. The AA-12 has a pistol grip and shoulder stock and a easy-sighting system. Slug rounds can extend the maximum range up to 100 meters. Rubber slugs for prisoner capture can be used up to 75 meters. The AA-12 can fire from a 10-round detachable box magazine or a 20- or 32-round ammunition drum, attaining a rate-of-fire up to 300 rounds-per-minute while having almost no muzzle climb and a dampened recoil effect. It is reported that even an infantryman weighing in at 100lbs can fire the weapon due to the near-zero recoil afforded by the weapon.
The AA-12 has been designed as a durable and dependable, well-built and well-machined shotgun to withstand the various battlefield rigors centering in on climate, weather, water and general grime. It is essentially a "point-and-shoot" weapon that can even be fired whilst upside down. The operation is via a simple blowback mechanism with an advanced primer ignition. To reduce the highest amount of recoil as possible and maintain the listed cyclic rate-of-fire, the firing pin was built into the bolt itself causing the firing pin to extend and ignite the round prior to the bolt closure. The long recoil system allows the bolt to travel further back than most weapons, hence the dampened recoil effect. The trigger group mirrors that of the BAR-1908 auto rifle allowing for semi- or full-automatic firing modes. It is designed to fire three different types of 3" or 2.75" 12 gauge shells - buckshot, standard slug, or Frag-12 rounds. Due to the metal parts being stainless steel, MPS has claimed that the weapon requires zero cleaning or lubrication - a major plus in combat situations.
When used in an urban environment, that is going door-to-door, a system for door-breaching is almost a necessity on today's modern battlefield (particularly showcased in recent actions in Iraq). The AA-12, therefore, is provided with a muzzle extension to press the barrel firmly against the door while providing protection to the operator when firing. Rounds for breaching doors with minimal hazard to any occupants within the room are also part of the AA-12 munitions package, helping to reduce the risk of collateral damage.
The AA-12 is currently being reviewed for purchase by the United States Marine Corps.