TRANSFORM YOUR AR PLATFORM WITH...
THE AUTO 12 & 20
The AUTO 12 & 20 are a proprietary upper receiver conversions that transform any standard AR-15 or DPMS AR-10 lower into a smooth, hard-hitting shotgun. Engineered for maximum performance and maximum fun, they use custom polymer shotshells designed to cycle flawlessly in a custom box magazine. Whether you’re dialing in your home defense setup or want something wildly fun, the AUTO 12 & 20 deliver a completely new experience, without a new firearm.
powered by patented rebated rimless all polymer custom shotshells
Available in 2026
Click below to learn more or schedule a test.
Seamless Conversion
Fit any DMPS Pattern AR-10 or Standard AR-15 lower. There’s no need for tuning. Just change the upper and shoot. It’s that simple and that fast.
Fast. Clean. Semi-Auto
Up to 10 rounds, box-fed, and gone in a flash. The Auto 12 & 20 cycle smoothly and hit hard, with zero lag, and a lightning fast recovery.
Engineered to Run
From the bolt design to the ejection geometry, everything was rethought to work perfectly on traditional AR lowers, reliably, every time.
Purpose-Built Ammo
The Auto 12 & 20 use custom 12 and 20 gauge polymer shotshells molded for flawless feeding, cycling, and ejection. And built tougher than brass.
AUTO 12 & 20 TECHNICAL SPECIFICATIONS
UNLEASH THE POTENTIAL OF YOUR AR Platform
Technical Specifications
- Gauge: 12-Gauge & 20 Gauge
- Compatible Platform: Any DMPS AR-10 or mil-spec AR-15 Lower Receiver
- Barrel Length: 18 inches. Short barrels coming soon
- Barrel Type: Smoothbore
- Choke Compatibility: Threaded
- Receiver Material: Billet Aluminum
- Finish: Hardcoat Anodized
- Action Type: Semi-Auto
- Operating System: Direct Impingement
- Magazine Type: Detachable Box Magazine
- Magazine Capacity: 5, 8, and 10 round magazines available
Included Components
- Complete 12 or 20-Gauge Upper Receiver
- Proprietary Bolt Assembly
- No Additional Buffer or Spring Required
- Two Magazines Included
- Owner’s Manual / Installation Guide
Testing & Compliance
- Tested with Butler Defense Custom Polymer Shells
- Compliance Notes: Upper receiver only; not classified as a firearm under federal law*
Installation & Compatibility
- Installation Time: Under 2 minutes
- Tools Required: None (standard AR push-pin installation)
- Made in: Sun Valley, Idaho, USA
Designed by a Shooter. Built by Butler
Meet Larry
A lifelong shooter and an engineer by trade. Larry Butler has been designing shotguns since the 1990s, one idea at a time. The AUTO 12 & 20 are the result of years of work, testing, and obsessive iteration. It wasn’t made for a quick launch. It was made to work. It’s the product of obsessing over doing it right.
And if you want to hear more, he’s happy to chat. Just give him a call.