(27 reviews) Write a Review


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.
Click Here

Don't Have a barrel, want one?  We have you covered.
Click Here


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.






27 Reviews Hide Reviews Show Reviews

  • 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.

  • 5

    Posted by Adolfo Garcia on Oct 5th 2019

    Thanks ester defense
    This item is great I revived and used 250 rd and not even menor issue MAG-AD9

  • 5
    Very pleased with fit and operation. A++++++

    Posted by Donnell Mitchem on Sep 27th 2019

    Being ex-law enforcement, we strive to find the best products on the market for our customers . A large majority of them are current LEO, Military and EMS so it is a huge pride thing for us to be able to build and mod their platforms. Don't think we aren't concerned about our other civilian customers; that would be an outright lie. Every build, every mod leaves our hands as if we were going back in harms way with it. We buy and test products before we ever offer them for sale to make sure we offer the best parts available. If they can handle what we do to them, then you should never have a problem. Upon testing, we are very pleased to announce we will be stocking these in our shop. The fit and funtion is far superior over anything else I have seen of its kind. Add the fact that they have several magazine platforms to choose from; it is going to make building your dream AR a reality. Thank you.

  • 5
    Very Pleased, No Issues, Very well made

    Posted by Jean-Luc Calouro on Sep 20th 2019

    First time to the range with no malfunctions at all. This is very well made and install was very easy.

  • 5
    Stern Defense AD9

    Posted by Phillip Davis on Sep 9th 2019

    I was skeptical at first but after using the AD9 it works flawlessly. it gives me the capability of using one lower for multiple calibers. Thank you Stern Defense for making a great product.

  • 5
    Best on the market!

    Posted by Ben on Aug 22nd 2019

    I've spent hours online researching who make the best adapter.. These guys and girls are the best!!! Well made, and very,very good customer service! I couldn't be happier!

  • 5
    AR 9MM conversion

    Posted by Steven Walker on Jul 27th 2019

    This worked great with my PSA lower and 9MM upper. Only 1 jam out of 100 rounds but appeared to be due to the magazine I was using. I would recommend!!