Review: Stern Defense AR Glock MAG-AD9 Adapter

By on April 12, 2018

In this review article, we are going to check out the new AR Glock Mag Adapter from Stern Defense. I have seen other AR Adapters on the market before from other companies. However, Stern Defense’s appears to be superior. Stern Defense not only offers a Mag Adapter for Glock Mags, but they also have Smith & Wesson M&P magazines as well.


The MAG-AD9 installs very quickly; you insert it into your magwell like you would any other AR magazine. Once installed, there are three hex screws on the bottom to tighten to hold it into place.

Once inserted you tighten this screw and the Delrin block on the front face of the mag adapter pushes up against the inside of the magwell thus wedging the adapter in place.


Then you tighten the two small set screws you see along the bottom edge of the mag adapter (top edge in photo). This prevents the mag adapter from shifting upwards.

Stern Defense MAG-AD9

The magazine release also gets relocated as well. As you can see below, there is a magazine release on the bottom right-hand corner. This is the release you will use for your Glock magazines.

Stern Defense

The best part about the MAG-AD9 Stern Defense is that the mag adapter doesn’t require any removal of parts from your already built AR lower. You will have to get a new 9MM upper with the appropriate barrel and bolt carrier group.

Stern Defense MAG-AD9 Install

(Now for the legal disclaimer our lawyer says we have to include)

When picking out a barrel, you have to be aware of the length. The National Firearms Act classifies any AR-15 having a barrel length under 16″ or an overall length under 26″ with collapsible stock extended as an SBR and is listed as an NFA item.

Owning an SBR is not illegal, You have to fill out a Form 1 to register a dedicated lower as your SBR and write the BATFE a check for $200 to buy a tax stamp.

It’s your responsibility to know your local state law. We take no responsibility.

Alright back to the review.

In our testing, the MAG-AD9 performed great. We didn’t have any troubles with it. It installed very fast and painless and shot great. We didn’t have any feeding problems, and the last round bolt hold open is a great touch. That is one thing that is hard to find on some dedicated AR 9MM Lowers.

The only downside about their adapter is the price. They are sold for $179.99 on Stern Defense’s website. You can get a dedicated 9MM AR lower for not that much more, and a stripped AR 9MM Lower can be bought for less.

Also, if you already have a registered SBR lower or a full auto lower, then $179.99 isn’t a bad price to be able to use Glock or M&P magazines.

I do still think they are worth checking out; it is a reliable adapter that performed great. And 9MM is a lot cheaper to shoot, so it makes a nice range plinking gun.

For more information check out their website. Also, follow their social media profiles and stay up to date with any new releases they might have coming out.

Check out Stern Defense and the MAG-AD9 Adapter here:

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