Q&A for Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter

Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter

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fakrwee, member, from FL, United States, asked on May 23, 2019

This might seem like dumb question but here goes. I want to convert my AR to shoot Glock 40. Besides this kit, I would have to buy a barrel, correct?

Expert Answer

Answered by Jonathan D., Gear Expert, from IL, United States, on September 23, 2019

You would need a barrel, a BCG, and most likely a heavier buffer.

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Jon Rathke, member, from MO, United States, asked on May 25, 2025

Will S&W magazines work with this?

Answered by Stern Defense, member, from MO, United States, on July 21, 2025

This MAG-AD is for glock magazines. You will need the MAG-ADMP9&40/P20 one for 9mm S&W magazines.

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Chris, guest, from KY, United States, asked on December 21, 2020

Will this adapter accept the shorter g26 mags as well, or will it only accept g19 size and up magazines?

Expert Answer

Answered by Davis N., Gear Expert, from IL, United States, on February 08, 2021

Glock 26 mags are too short to be used with this.

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Anon, member, from SD, United States, asked on April 05, 2026

what 30+ Rd Magazines work with this; confirmed.

Answered by Stern Defense, member, from MO, United States, on April 08, 2026

We only recommend factory Glock magazines.

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BoBoGadget, member, from TX, United States, asked on March 06, 2026

So if I have a .223 Ar and want to use this on my rifle what all do I need? Or do I just put the 9mm mag in this and put in to my Ar and all good.

Answered by Stern Defense, member, from MO, United States, on April 08, 2026

You need a caliber-specific bolt and barrel. We also recommend running a heavier buffer (5.4 oz) for 9mm. Most people buy a complete 9mm upper with it.

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Johnnie, member, from OH, United States, asked on November 01, 2025

how does it secure in the magwell on ar

Answered by Stern Defense, member, from MO, United States, on April 08, 2026

It clicks into place like a magazine using the existing factory mag catch. It also has a set screw at the bottom that you tighten, which pushes out an anti-vibration gib.

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oneofnunn, guest, from CA, United States, asked on August 03, 2025

What exactly holds this into the lower receiver is it the ar magazine catch or is their something like the Sullivan one that take the tiny Allen screw

Answered by YankeeBluejeans, member, from MN, United States, on October 19, 2025

It clicks into the lower's mag catch, yes. Then it has three screws to lock it in place. It won't damage your lower's finish.

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Cowboyrks718, member, from TX, United States, asked on January 12, 2025

Will theses adapters work with a foxtrot mike upper. I am using endo mags but they are a pain to load.

Manufacturer Answer

Answered by STERN DEFENSE, Manufacturer from MO, United States, on March 26, 2025

We sometimes see issues with the stripper lug size on their bolts. Some of their bolts are just fine and others the stripper lug is set too high on. Please check out our FAQs page to show where to measure on your bolt. Lug should be between .120 and .130. If you have a bolt that the stripper lug is high on please purchase our bolt mod service on our website and send us your bolt it is on $7.50 and that will fix the issue.

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CK, member, from SC, United States, asked on December 10, 2024

PMAG 10 GL9, Glock 17/19 10-Round 9mm Magazine compatible?

Manufacturer Answer

Answered by STERN DEFENSE, Manufacturer from MO, United States, on March 26, 2025

We only recommend factory magazines with our MAG-ADs.

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Brian, guest, from AR, United States, asked on November 26, 2024

Does this adapter have last round bolt hold open.

Manufacturer Answer

Answered by STERN DEFENSE, Manufacturer from MO, United States, on November 27, 2024

Yes, it works great!

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Q&A for Stern Defense MAG-AD9 AR-15 Glock 9mm/.40 Magazine Conversion Adapter — 34 Questions & 37 Answers