Stern Defense Mag-AD9 9mm Glock Magazine Adapter for AR-15


4 in stock

(6 customer reviews)

With the Stern Defense Mag-AD9 adapter, you can easily convert your AR-15 into an AR-9. Unlike other 9mm adapters, the Mag-AD9 is made from lightweight 6061 T6 aircraft grade aluminum which means it’s built for longevity and reliability. With premium features like last round bolt hold open (LRBHO) and an easy to reach mag release, the Stern Defense Mag-AD9 is the only choice for an AR9 conversion!

4 in stock


  • Installs quickly, easily, and most importantly, securely into any mil spec AR-15 lower receiver.
  • Designed from the ground up to work with AR-15 and M16 mil-spec upper receivers.
  • Made in the U.S.A.
  • 4140 NiB coated feed ramp.
  • Hard coat anodized type 3.
  • Sturdy Construction.
  • Works with all generations of Glock magazines*

Requires 9mm barrel and Glock cut bolt*

Additional information

Weight 9.3 oz


Why We Love It

The Stern Defense MAG-AD9 is an amazing bit of engineering. When our buyers met with the representatives at Shot Show 2018 and were shown the MAG-AD9 magazine adapter we new it was going to be a  hit among shooting enthusiasts. The ability to turn an AR-15 lower receiver into a Pistol Caliber Carbine (PCC) was not a new or unique idea at the show. We looked at several idea models by multiple manufacturers. None came close to the quality of design and materials of Stern Defense.

Stern has created a solid mag well insert the securely locks into place. There is no rattle or slop. Essentially, it becomes part of your gun.

Later, when we had time to put it through it’s paces, the Stern Defense MAG-AD9 ran flawlessly. It chambered every bit of 9mm ammo we could throw at it. We tried several aftermarket Glock magazines and none even caused the MAG-AD9 to skip a beat.

In conclusion, if your looking for a way to turn your AR-15 into an AR-9 without buying a new lower receiver, look no further than the Stern Defense MAG-AD9.


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The Daily Shooter review from

6 reviews for Stern Defense Mag-AD9 9mm Glock Magazine Adapter for AR-15

  1. Sgt. JC (store manager)

    This is by far the best 9mm mag well adapter I’ve used. It’s currently in my latest AR9 build (5.5″ barrel). Works flawlessly when setup correctly.

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  2. Randy D. (store manager)

    Took my rig out for a 2nd round of testing this past weekend, and could not be happier. Very smooth, reliably holds the bolt open on an empty mag, and flawless feeding.

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  3. George A. (store manager)

    Just bought one…fit snugly, simple to install, having a problem with lock mechanism, it did not lock all the magazines in. Some magazine fit other did not, a little disappointed about this. the ones it does take work well, but not happy the overall. For the price I expected a lot more, a dedicated lower might be a better way to go than this conversion box.

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  4. Andrew G. (store manager)

    This adapter is made of quality materials and it is easy to install and remove. What I had trouble with was the magazine catch it did not consistently lock the magazine into place. The newer magazines it works like a charm but with some older “U” style magazines and I refer to them as the Glock Gen 1-2 magazines here will not lock in and in some case will not fit into the magwell. I am not sure these issues can be fixed but it is an issue which the company should be more specific about before you purchase this expensive adapter.

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  5. Melissa M. (store manager)

    first AR 9 build, and really not fond of adapters, but i have to say at just over 2000 rounds the Stern Defense Mag-AD9 9mm Glock Magazine Adapter has had 0 failures, has stayed secure in the mag well, last round bolt hold up has never failed. gen 2 to gen 4 glock mags as well as other after market 31 and 33 round mags worked flawlessly and dropped freely. no feed problems using 115 to 147 round nose or hollow point ammo. AR 9 faxon BCG, Anderson lower, PSA 16″ barrel, SW A3 upper receiver, 9mm buffer, mil spec FCG with a DIY polish on the trigger, hammer, and disconnector. this adapter is a bit pricey, but for what i wanted and with transfer fees still came out about 60.00 cheaper then buying a dedicated glock lower and out performs some. great buy.

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  6. Ryan P. (store manager)

    Works great. Easy to install

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