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Convert your standard mil spec AR 15, M4, M16 lower assembly to use 9mm and .40 S&W Glock Magazines!  The Mag-AD series adapters install in seconds.  Boasting a last round hold open feature making them a breakthrough product and a must-have for law enforcement and civilian gun enthusiasts alike.

The Stern Mag-AD9 series adapters are made of aircraft grade aluminum, lightweight with ergonomic design.   

Note: These adapters require the use of a 9mm or 40S&W barrel, "depending on chosen caliber" and a Glock cut bolt.


Looking for a complete conversion kit?  We have you covered.
Click Here.

Already have a Colt Style bolt and want to use our system?  We have you covered.
Click Here

Don't Have a bolt, want one?  We have you covered.
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Don't Have a barrel, want one?  We have you covered.
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Technical Information:

⦁    Made in the U.S.A.

⦁    Constructed from 6061 T6 aircraft grade aluminum.

⦁    4140 NiB coated feed ramp.

⦁    Hard coat anodized type 3.

⦁    Sturdy Construction.

⦁    Ergonomic mag release.

⦁    Works with any mil spec ar15 lower receiver.

⦁     All gun components besides the Bolt and Barrel remain stock

Please visit the following link before purchasing to ensure compatibility with your setup.






52 Reviews Hide Reviews Show Reviews

  • 5
    Stern 9mm conversion

    Posted by Mitchell Davis on May 4th 2021

    Easy install. Works great. Feeds great.

  • 5

    Posted by Drew on Apr 26th 2021

    Cycles perfectly, once you set it up it stays in place through a tons of rounds, haven’t had to readjust since I got it!

  • 5

    Posted by William Palacio on May 25th 2020

    There were 2 of this product one of them is from Stern Defense the MAG-AD9. After much search and compare its product. I found that the Stern was suited for my own liking compare to the other one I was looking into. When I finally received the MAG-AD9 I was impress if the quality that it's made from. I test fitted it I was happy with it glad I bought this from Stern. Great addition to my new AR9.

  • 5
    Mag Well Adapter - Am I nuts?

    Posted by RoCo on May 15th 2020

    First thoughts after unboxing. This thing costs more than some dedicated lowers. Am I nuts?
    After i popped this into my lower with a specialty trigger, I felt a whole lot better! This thing is real....and I didn't have to buy a new lower, or trigger, etc, etc.
    LRBHO is awesome. Fit and function are perfect.

  • 5
    MAG-AD9 Mod4 8.5 barrel.

    Posted by Lewis on May 15th 2020

    Received the MAG-AD9 and Mod4 9mm Upper yesterday. Put it on my BCM Pistol lower and ran 100 rounds through it. It was flawless!
    Going to get a designated lower for it so I can leave it assembled.

  • 5
    9mm mag well adapter

    Posted by Bernard on May 11th 2020

    Installed using instructions and it worked perfectly!

  • 5
    Very well engineered product

    Posted by Chris on May 6th 2020

    Very very nice product

  • 5
    Great product

    Posted by Evan Zimmerman on Jan 17th 2020

    Purchased the mag adapter. Dropped right in and works the way it is supposed to. Appears to be built very well. Bolt hold open feature is why I made the decision to purchase over others. Very impressed.

  • 4

    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