Frequently asked questions
What lowers are compatible with the AUTO 12 & AUTO 20?
The AUTO 12 & 20 are designed to fit any standard mil-spec AR-15 or DMPS Pattern AR-10 lower. No tools, tuning, or modifications are required. Just push a a few pins and you’re ready to run.
Do I need to change my buffer, spring, or trigger group?
No. The AUTO 12 & 20 use their own internal system that works with your existing AR lower components without adjustment.
Can I use my standard AR charging handle or bolt?
No. The AUTO 12 & 20 comes with their own proprietary bolt assembly and internal components. Your AR lower stays the same, but the upper is purpose-built.
What’s the barrel construction and choke setup?
The barrels are 18 inches, smoothbore, and threaded for Rem-Choke compatibility. Short barrels available soon.
Can I use regular 12 or 20-gauge shells?
No. The AUTO 12 & 20 are designed to run on Butler Defense’s proprietary rebated, rimless polymer-cased shotshells. These are specifically engineered for clean cycling and safe use in this platform.
Are slugs and buckshot available?
Yes. Various loads are available with more to come. Contact for more information.
Can I reload your shells?
For reloading information, please contact us directly.
Can I use aftermarket AR accessories on the AUTO 12 & 20 uppers?
Yes. The upper uses standard AR-height Picatinny rails and accepts most free-float handguards and top-mounted optics.
Are the AUTO 10 & 20 good for home defense?
Yes. Shotshells reduce recoil and overpenetration risk while maintaining serious stopping power. It’s fast, familiar, and easier to control than larger calibers in close quarters.
Do the AUTO 12 and 20 count as firearms?
No. The AUTO 12 & 20 are upper receivers only. They are not serialized and not considered a firearm under federal law. They attach to your existing AR lower, which is the serialized part.
Where are the AUTO 12 & 20 made?
Every Butler Defense upper is hand-built in Sun Valley, Idaho.
Who designed it?
The AUTO 12 & 20 were designed by Larry Butler, a lifelong shooter and engineer who’s been building shotguns for over 30 years. This platform is the result of years of real-world testing and refinement.