Reviews & Ratings for Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter

Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter

List: $237.99 $179.99 Save 24%

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Most Helpful Positive Review Stern Defense has the best customer servise!

Purchase this adapter for my AR 9 build. Had issues with jamming if I put more than 3 rounds( didn't matter if flat or round nose) in the mag. Re-installed the adapter three times and had the same result every time. Called Stern Defense left message and though well that was a waste of time, but t...
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Most Helpful Negative Review Feed issues

While it is well built, I could not get HP or flat tip rounds to feed without lots of jams. And the jam is actually within the adapter itself. The small feed ramp it has built in it has a very sharp edge on the bottom. I tried three different brands of glock mags. All would every so often do the sa...
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Stern Defense Magwell Adapter

by t, Verified Owner from WV, United States Written on August 1, 2026

This is my third stern Glock magazine adapter. I don’t believe I have ever ran into a single problem with any of these adapters. They feed reliably in many different lowers. I have use many different sized magazine-counts and brands as well; KCI, Glock brand, ETS, P mags, etc. It runs them all, also works with binary trigger lowers I have so probably frt too

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Nice product but....

by Kenny, Verified Owner from NY, United States Written on July 20, 2026

It fits nicely in my Anderson lower but will NOT work with a Foxtrot Mike 9mm Upper. The feed ramp on the Stern Defense Adapter will hit the BCG on a Foxtrot Mike Upper. I googled it and it is documented by Stern Defense, they will actually have you send them your Foxtrot Mike BCG and they will machine it so it clears their feed ramp.I just decided to return the adapter and cough up an extra $50 for a 9mm lower.

Pros:

Fits a Anderson Lower

Cons:

Will not work with Foxtrot Mike 9mm Upper

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AR9 Mag Adaptor

by Liccian, Verified Owner from VA, United States Written on June 30, 2026

Installed this to a standard AR lower. Completer my AR9 build. Took it the the property and it worked flawlessly. Love the quality and functionality.

Pros:

fitment

Cons:

Can't easily swap

Best Used for:

MilSpec Lower

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works great

by Dave, Verified Owner from OH, United States Written on May 20, 2026

Works great. Perfect fit in my AR lower. I added a bullet button to the receiver to prevent me from accidentally dropping the adapter.

Pros:

Works perfectly

Cons:

none so far

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Nice adapter

by Mike, Verified Owner from TN, United States Written on April 27, 2026

This adapter was easy to install. Works well in my Anderson lower. Doesn't fit the clear off brand mags (Titan?), but it does fit pro mag and KSI, and of course all glock mags work well in it. The release is a little stiff but hopefully that will wear in. Overall I'm very happy.

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Very Well Designed and Made

by Y3, Verified Owner from AL, United States Written on April 21, 2026

Very well made and is a high quality and simple solution to being able to use glock style mags in the AR. All functions work as they should including LRBHO. I like the flexibility and versatility of this product and being able to use Endomags or ExoMags if I choose.

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Mag-AD9 Review

by Mark Fisher, Verified Owner from CO, United States Written on March 5, 2026

Well made, easy installation and awesome functionality.

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Non-Adjustable Ejector, Useless Customer Service at Stern

by Boy Knee Sand Is, Verified Owner from OH, United States Written on February 27, 2026

This product is way overpriced for not being able to adjust the height of the ejector, and Stern customer support was useless.
I tried installing this in my setup that has a mil-spec upper and lower and even a Stern bolt but the ejector sat like 1/16" lower than it should in the bolt cutout. I tried reaching out to Stern to see if they had a solution and they responded at first but then ghosted me without a resolution.
Don't waste your money gambling on an expensive adapter that can easily be defeated by tolerance stacking. Just get a dedicated lower.

Pros:

quality machining

Cons:

lacks adjustability

Best Used for:

Paperweight

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Mike Harrison

by Michael Harrison, Verified Owner from PA, United States Written on January 2, 2026

The production fitment was perfect!! I can’t wait to try the functionality.

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Works greats

by Tom, Verified Owner from OH, United States Written on January 1, 2026

The mag adapter is very well made, easy install and stays in place

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Reviews & Ratings for Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter — 86 reviews — Page 1