- STERN DEFENSE is a specialty manufacturer committed to precision, quality, and efficiency of the weapon accessories created.
- Using the best USA supplied material our products are designed and manufactured by the finest machinists and engineers in the industry.
- We are dedicated to law enforcement, hunters, shooters and gun enthusiasts across this great nation.
- Our values are traditional, rooted, firm and STERN.
How we got started
Before dedicated pistol-caliber lowers existed, our father prototyped a magazine adapter so an AR-15 could feed the same magazine as a service pistol. He had law enforcement in mind: one magazine for the sidearm and the rifle.
We took the prototype to SHOT Show, and people wouldn't put it down. That adapter became the MAG-AD, and its design has been patented since 2018. We formed Stern Defense in 2016 and shipped our first orders in 2017.
What we make
MAG-AD magazine adapters. The MAG-AD drops into a mil-spec AR-15 magwell and lets the rifle feed pistol magazines, with last-round bolt hold-open built in. There's a version for each magazine family: the MAG-AD9 for Glock 9mm and .40 S&W, the MAG-ADMP9&40/P320 for S&W M&P 9 and 40 and SIG P320, the MAG-ADMP45 for M&P 45, and the MAG-ADB92 for Beretta 92 and M9.
Complete uppers and conversion kits. 9mm, .40 S&W and .45 ACP uppers from a 4-inch pistol barrel to a 16.1-inch carbine, each assembled with a Stern Defense barrel, bolt and charging handle and test fired before it ships. A conversion kit pairs the upper with the matching MAG-AD in one box. Key Components kits carry the barrel, bolt and MAG-AD for builders who already have an upper receiver and handguard.
The RAB-AD series. The Rapid Attach Buttstock Adapter lets you take a stock or brace off an AR in a couple of seconds and put it back on, no tools, no modifications to the rifle. Push the button, twist a quarter turn, and it's off. It's machined here from 7075 aluminum with steel internals, adds about an inch and a quarter to length of pull, and weighs three and a half ounces. It comes in three versions: the full-size RAB-AD for standard AR buffer tubes, the RAB-AD Mini for compact takedown setups, and the RAB-AD Pic Rail for receivers with a Picatinny rail.
The H2S trigger. Our Hybrid 2-Stage drop-in trigger sits between a mil-spec trigger group and a competition trigger: a 2-pound first stage into a 4-pound second stage, a crisp break and a predictable reset. We designed it with pistol-caliber carbines and defensive shooters in mind and ran it through a 250,000-round test without a failure. It fits AR-15 and AR-10 lowers with standard pin sizes, and a lighter 3-pound spring is in the box for rifle-caliber builds. It's available with a cold nitride finish or nickel boron.
Barrels, bolts and small parts for people building their own 9mm, .40 or .45 uppers, plus spares for everything above.
Who we are
Stern Defense is a family-owned company in Summersville, Missouri, and it's majority woman-owned. We formed the company in 2016 and started selling in 2017, and we still design and build our parts in the same town.
How our products get made
Our adapters, the RAB-AD and the H2S are designed, machined and assembled at our shop in Summersville. Each MAG-AD is put together by hand, because it fits a lot of parts into a small space. Every complete upper is test fired before it leaves.
New products come from two places: something we wanted on our own rifles, and a customer asking whether we make an adapter for their magazine. More than one of those questions became the next product.
Every Stern Defense product carries a one-year warranty against defects in materials and workmanship, to the original purchaser.
Who we build for
Our customers are shooters who already own an AR-15 and want more out of it: a 9mm upper for cheaper range days, an adapter that runs the same magazines as their pistol, a stock that comes off for the case, or a trigger that feels the same on round one and round ten thousand. That includes law enforcement, competition shooters, and people who just like building rifles. We're happy to talk through a build before you order, and our compatibility page has the measurements to check your lower first.
Facts about Stern Defense
What does Stern Defense make?
Magazine adapters, complete uppers and conversion kits that let a mil-spec AR-15 run 9mm, .40 S&W or .45 ACP; the RAB-AD Rapid Attach Buttstock Adapter series; the H2S Hybrid 2-Stage drop-in trigger; and barrels, bolts and small parts.
Who owns Stern Defense?
Stern Defense is a family-owned LLC in Summersville, Missouri, and it is majority woman-owned. It is an independent company, not a subsidiary or division of another business.
When was Stern Defense founded?
The company was formed in 2016 and began selling in 2017.
Where are Stern Defense products made?
Adapters, the RAB-AD and the H2S trigger are designed, machined and assembled at our shop in Summersville, Missouri. Complete uppers are test fired before they ship.
Is the MAG-AD patented?
Yes. The MAG-AD design has been patented since 2018.
What is the RAB-AD?
A two-piece coupling that lets you detach and reattach an AR stock or brace in seconds without tools. It comes in full-size, Mini and Pic Rail versions.
What is the H2S trigger?
A drop-in Hybrid 2-Stage trigger for AR-15 and AR-10 lowers, with a 2-pound first stage and a 4-pound second stage, tested to 250,000 rounds.