TRANSFORM YOUR AR-15 WITH...
THE AUTO 20
The AUTO 20 is a proprietary upper receiver conversion that transforms any standard AR-15 lower into a smooth, hard-hitting 20-gauge. Engineered for maximum performance and maximum fun, it uses custom polymer shotshells designed to cycle flawlessly in a 7-round box magazine. Whether you’re dialing in your home defense setup or just want something wildly fun at the range, the AUTO 20 delivers a completely new experience, without a new firearm.
A NEW KIND OF FIREPOWER
Elevate Your Shooting Experience
The AUTO 20 doesn’t just change calibers. It changes behavior.
The sound, the feel, the way it handles. It cycles fast, hits hard, and runs like it was made just for you. It’s everything you love about your AR with a completely new signature. And a payload that changes the game, round after round.
You’ll know after one pull of the trigger.
Seamless Conversion
Fits any AR-15 lower. There’s no need fot tuning. No spring swaps. Just push two pins and shoot. It’s that simple and that fast.
Fast. Clean. Semi-Auto
Seven rounds, box-fed, and gone in a flash. It cycles smooth and hits hard, with zero lag, no hesitation, and fast recovery.
Engineered to Run
From the bolt design to the ejection geometry, everything was rethought to work perfectly inside an AR-15 reliably, every time.
Purpose-Built Ammo
Our custom polymer 20-gauge shotshells are molded for flawless feeding, cycling, and ejection. And built tougher than brass.
SAWTOOTH STRONG
Hand-built in Sun Valley, Idaho by engineers who shoot.
Every AUTO 20 upper is crafted by hand in Sun Valley, Idaho by the team at Butler Defense. The result is a weapon system that’s engineered, not improvised.
It’s not mass-produced, and it’s not rushed. It’s a precision tool with a personality. And it’s built by people who live in the mountains, work at the bench, and shoot what they build. From the powder in the shells, to final coat of paint, it’s American engineering with real-world intent.
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. Not in a factory, but one idea at a time. The AUTO 20 is the result of years of work, testing, and obsessive iteration. It wasn’t made for a launch. It was made to work. It’s the product of one man’s obsession with doing it right.
And if you want to hear more, don’t worry, he’ll tell you about it.
