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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 all generations of Glock magazines.

⦁    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.






51 Reviews Hide Reviews Show Reviews

  • 5

    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

    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

    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

    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...

  • 5
    Love it, only had one minor issue

    Posted by John Lin on Oct 23rd 2019

    Love it. I think this is the only magazine adapter with last bolt open. Very easy to install. After installing it, empty magazines weren't catching and would just pull out. I had to hit the bottom of the magazine several times for it to seat. After that the magazines fit and seat perfectly. I wish there was a slight cant outerward to the magazine release button. It would feel more natural and save your finger tips after several releases.

  • 5
    Great product

    Posted by Walt on Oct 11th 2019

    Love it. While waiting for parts to finish my build placed it on another ar pistol and is so easy to change back and forth.