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Reviews & Ratings for Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter — 82 reviews

(82 reviews)
Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter
Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter
$258.57 $179.99 Save 30%
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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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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.
Would recommend: Yes
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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.
Would recommend: Yes
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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.
Would recommend: Yes
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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
Would recommend: No
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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.
Would recommend: Yes
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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
Would recommend: Yes
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works better than expected

by Courtney Good, Verified Owner from IN, United States Written on December 12, 2025
Fits tight and works like it should. Can run ball and hollow point with it.
Would recommend: Yes
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Sterner 9mm conversion

by Hawks, Verified Owner from WI, United States Written on August 21, 2025
I had another 9mm conversion adapter, and had enough issues. Double taps without trying, failure to feeds, frustrated. Ran this , and so far no issues so far.
Would recommend: Yes
1 of 1 found the following review helpful.
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doesn't work with cmmg banshee uppers

by Josh A, Verified Owner from AL, United States Written on August 2, 2025
Doesn't work with cmmg banshee uppers, but no where is it mentioned that it will only work with certain 9mm bolts. Waste of time and money. Returning asap.
Would recommend: No
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No more failure to feed issues!

by cz1970, Verified Owner from KY, United States Written on July 22, 2025
Tried to use Endomags on my 9mm pcc build. I could never get them to be even close to reliable. Just bought another pcc that takes Glock mags, so I decided to convert my stock 556 lower to Glock mags with this Stern Defense adapter. I wish I would have went this direction in the first place. It is very easy and quick to install and I have had no ftf issues.
Would recommend: Yes
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