Mag-AD 9mm / .40 S&W Glock Magazine Adapter

Revolutionizing AR Builds. Designed, Machined, and Assembled in Our Factory.

The Mag-AD 9mm / .40 S&W Glock Magazine Adapter is Stern Defense’s flagship product, the one that put us on the map. Trusted by law enforcement and civilian gun enthusiasts alike, this adapter allows you to quickly convert your standard mil-spec AR-15, M4, or M16 lower assembly to accept Glock 9mm and .40 S&W magazines.

Crafted entirely in-house at our factory, every aspect of the Mag-AD is meticulously designed and built to ensure superior performance, quality, and precision. The adapter boasts a last round hold open feature, a breakthrough innovation that elevates the shooting experience—making it a must-have for anyone looking to enhance their AR build.

✅ Why Choose the Mag-AD?

Quick Installation: Installs in seconds, transforming your AR-15 lower into a 9mm or .40 S&W Glock mag-compatible firearm
Last Round Hold Open: A critical feature for reliability and functionality, ideal for both law enforcement and civilian use
Lightweight & Ergonomic: Constructed from 6061 T6 aircraft-grade aluminum for optimal performance and comfort
Durable: Features a 4140 NiB-coated feed ramp and Type 3 hard coat anodization for wear resistance

⚙️ Technical Information

Material: Constructed from 6061 T6 aircraft-grade aluminum
Feed Ramp: 4140 NiB-coated for durability
Finish: Hard coat anodized Type 3 for maximum wear protection
Mag Release: Ergonomically designed for ease of use
Compatibility: Works with any mil-spec AR-15 lower receiver
Bolt and Barrel: Requires a 9mm or .40 S&W barrel (depending on caliber) and a Glock-cut bolt
Stock Components: All components remain stock, except for the bolt and barrel

⚠️ Important Notes

Buffer Requirement: Must be used with a 5.4-ounce buffer or heavier when using a carbine spring.
Click here for the recommended buffer
Compatibility Check: Be sure to check compatibility with your setup before purchasing.
Click here to confirm compatibility

✅ Looking for a Complete Conversion Kit?

We’ve got you covered with everything you need to get started.

Transform Your AR Build Today

The Mag-AD 9mm / .40 S&W Glock Magazine Adapter is more than just a product—it’s an essential upgrade for anyone looking to get the most out of their AR-15 build. Whether you’re in law enforcement, competition shooting, or a civilian enthusiast, Stern Defense brings you the best in quality, performance, and reliability—all crafted right here in our factory.

53 Reviews Hide Reviews Show Reviews

4
MAG-AD-9

Posted by Terry Patrick on Jan 16th 2020

Solid, well worth the money. Will buy a 45 in the future. The only reason I gave it 4 stars, is that I don’t give 5. I would buy it again
4
9 mm adapter

Posted by Terry Patrick on Jan 13th 2020

So far so good. First time out, two FTF, probably my reloads. Well built adapter. Looking at getting a 45 a piece adapter
5
MAG-AD9

Posted by Anthony Davis on Jan 13th 2020

Excellent product, American ingenuity at its best.
Makes it easier to have a 9mm AR especially if you're on a budget!
5
MAD-AD9

Posted by Luke Hoffman on Dec 25th 2019

Get good mags and it’ll run good
5
Ordered the kit

Posted by Unknown on Dec 10th 2019

Ordered this in a kit and works perfectly so far. Installation is simple and has had 0 failures of any kind through 200+ rounds of factory, plated, coated or cast ammunition. Built heavy duty
5
MAG-AD9

Posted by Ron M. on Dec 3rd 2019

Works very well with every magazine I've tried. 100% function with 14 different loadings and 5 different size and/or brand mags. Well worth the money, with this and the Beretta 92 version I can pair any of my pistols with an AR style carbine.
4
Seems quality

Posted by Jacob on Nov 25th 2019

Works really well so far, only issue was upon initial installation I had an issue where I couldn’t cycle the action. But with some minor adjustments of the screws I was able to make it run smooth, overall would recommend
5
Mag-Ad9

Posted by Michael M on Oct 28th 2019

I have to say how pleasantly surprised I was with this mag adapter. To be honest, I didn’t have a ton of confidence on how smoothly this would operate. To my surprise, I didn’t have a single failure of any sort in my first range trip of about 200 rounds and that’s with magpul mags so that’s saying something!
It’s going to take a little getting accustomed to the location of the mag release but it’s comfortable and makes sense. It is absolutely incredible that you can have a 9mm ar and switch to a bunch of different calibers with one Allen key and a new upper in a matter of seconds!

Thanks Stern Defense,
I’m overjoyed at the simplicity and effectiveness of this product especially paired with your bolt and barrel.
5
.40 S&W Glock Mags

Posted by Ron Gilbert on Oct 24th 2019

Polished metal fed ramp. Installed <15 mins ran 500rds cycles like a Singer Sewing Machine...