The AA-12, or Atchisson Assault Shotgun, is one of the most fascinating shotguns to ever grace the scattergun genre. Surprisingly, the AA-12 came to life way back in 1972! It’s not a new design, but it’s one that’s been constantly updated and improved over time. The word “assault” likely perks some ears, as we all know assault rifles have automatic capability. Guess what? So does the AA-12. This full-auto-only shotgun can distribute a lot of lead in a very short period of time.

The AA-12 Inventor – Maxwell Atchisson

Maxwell Atchisson’s work mostly revolved around creating 22 caliber conversion kits for popular firearms. He famously produced a working 22 caliber-conversion kit for the M16. He produced and designed several other conversion kits, as well as producing a .22 caliber submachine gun and 9mm submachine gun. He worked at Military Armament Corporation, aka MAC, the creator of the popular MAC SMGs.

In the 70s, his efforts shifted towards producing the AA-12. He worked seemingly tirelessly on the design, but with little interest from military consumers, there wasn’t much in the way of R&D funds. His original AA-12s never left the prototype phase until a company called Military Police Systems purchased the rights to the design.

From there, we got the modern AA-12 we all know and, likely, love today. Military Police Systems dropped the Atchisson from the name and renamed it the Auto Assault 12. After 18 years and 188 changes and improvements, the AA-12 went from prototype to functional full-auto shotgun.

Spec Breakdown

The AA-12 is not a small shotgun by any means. It’s a heavy-duty fighting weapon that uses a non-traditional shotgun design. It features a hefty amount of polymer and uses a rifle-like layout with a pistol grip and forward magazine.

The barrel is 17.99 inches long, just a hair beneath the 18 inch NFA requirement. A CQB model was produced that featured a shorter and handier 13-inch barrel. An unloaded AA-12 weighs a hefty 10.494 pounds, and loaded weight varied greatly depending on ammo loaded and magazine size utilized.

The AA-12 utilized an ambidextrous top-mounted charging handle and an AR-style safety on the left-hand side. Iron sights are the most popular sighting solution, but red dot mounts exist as well to bring the Auto Assault 12 to the 21st century.

The AA-12, the Finer Details

This full-auto-only shotgun sounds like a nightmare at first. The recoil must be tremendous, and what if you only need one round of buckshot? Well, first, the firing rate was only 300 rounds per minute, which is half of the firing rate of a Kalashnikov. Such a slow firing rate allows users to easily fire a single shot.

Twelve gauge recoil often makes shotguns tough to handle. So used in full auto, it’d be too much of a pain to make it useful anyway, right? Well, no. The AA-12 famously uses a gas system that reduces 80 percent of felt recoil, and a recoil spring helps nab another 10 percent of recoil. The end-user only feels about 10 percent of the recoil normally associated with a 12-gauge shotgun.

Full auto eats a lot of rounds, so to keep the beast fed, the AA-12 was fed from an eight-round box magazine or a 20- or 32-round drum magazine. The eight-round box magazine and 20-round drum are the two most common options we’ve seen in AA-12 shotguns.

That full auto-only approach also uses an open bolt. Open bolt shotguns are quite rare, but open bolt systems are not. They are common for belt-fed weapons as well as submachine guns. And for a high-volume shotgun, an open bolt makes a tremendous difference and a lot of sense. Full auto guns get hot — real hot — and modern shotgun ammo uses a plastic hull. If that hull sat in a hot chamber, it could melt a bit and get stuck. Having it sit nice and tight in a magazine until it fires is a smart move.

The Ammo

One of the strengths of the shotgun platform is the multitude of ammo types it can utilize. As such, the AA-12 can utilize your normal buckshot and slugs. Users could manually cycle less-lethal rounds and similar underpowered munitions. This allows the shotgun to serve in a wide variety of roles. With buckshot, this thing takes trench brooming to a new level. It could disperse hundreds of 33 caliber balls in seconds and turn a roomful of bad guys into mincemeat.

The folks at Military Police Systems teamed up with Action Manufacturing Company and Special Cartridge Company to produce a unique FRAG-12 round. This explosive round turned the AA-12 into a full-auto mini grenade launcher. The max range of the FRAG-12 was 200 meters. These offer somewhat limited function compared to standard 40mm grenades but are much smaller and could be directly fired instead of arced into a target.

Can You Own an AA-12?

If you don’t want your own Auto Assault 12, you might not be American. Alas, our gun laws prevent us from owning a true AA-12 without having the necessary SOT and FFL license. Since these were all manufactured after the passing of the Hughes Amendment, ownership is highly restrictive.

However, a company out of Florida called Sol Invictus is trying to make dreams come true. They have been working on a Semi-auto, civilian-legal AA-12. The process is ongoing and was thrown a little off-kilter when another manufacturer sold AA-12s that the ATF determined to be machine guns.

Hopefully, we will all have the opportunity to own an AA-12 in the near future. Until then, we can hope, dream, and press on. The AA-12 might have been designed before I was born, but it’s undoubtedly one of the most modern shotgun designs ever.