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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.






53 Reviews Hide Reviews Show Reviews

  • 5
    Extremely well made

    Posted by Frank Perreault on Nov 14th 2021

    I was very happy with the build quality. It installed in the gun with no problems and worked like a charm. Couldn't be happier!

  • 5
    Ar-15 Mag Block for 9mm

    Posted by Gregory Lee on Oct 13th 2021

    This is a very high quality piece of equipment that works flawlessly. I will be purchasing another.

  • 5

    Posted by Deez N. on Oct 9th 2021

    Solid construction and flawless function. Works perfect with the psa gen4 9mm upper. No jams or fuss with ets glock mags. Would definitely reccommend.

  • 5

    Posted by Steve on Aug 3rd 2021

    No brainer. If you're unsure of this product then you haven't been paying attention. Buy it. If you buy a dedicated lower it most likely won't have last round hold open

  • 5
    AR mag adapter 9mm/40 s&w

    Posted by Marion D Richardson on Jul 27th 2021

    Works great for 40 cal. Carbine and no malfunction after 500 rds, if you want to build a pcc this is the magwell adapter you need.

  • 5
    MAG AD9

    Posted by Max on Jul 27th 2021

    Product is perfect. Vinyl adjustment screws make it a great fit. More importantly the customer service is outstanding. Highly recommend.

  • 5

    Posted by Duckstreet on Jul 27th 2021

    Works great!

  • 5

    Posted by Robby T on Jul 14th 2021

    Great product. I put this in my lower using a PSA 9 upper with Glock style BCG, and went at it. No jams at all. I was using the SD HB1-H3 BUFFER and it cycled great. The bolt release was a little stiff at first, but after a couple of mag changes, it loosened up. If you don't want to buy a dedicated 9mm lower, this is a great product. It's also a bonus that you don't have to use an FFL, as you would with a lower.

  • 5
    Stern Defense MAG-AD9

    Posted by Racky on Jun 7th 2021

    Installed this in my Eagle Arms lower. Tactical Solutions 16” barrel. Faxon Bolt. Magpul GL-9 mags. This thing rocks ran like a sewing machine not one hiccup.