Stern Defense Magazine Conversion Block – for Glock 9mm & .40 S&W Magazines

SKU: S01508

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Convert Your Lower Assembly To Use 9mm and .40 S&W Glock Magazines

This Stern Defense Magazine Conversion Block will allow you to convert your mil-spec AR 15, M4, or M16 lower assembly to be able to use 9mm and .40 S&W Glock Magazines in your standard AR-15 lower receiver.

This Magazine adapter can be installed and offers a last-round hold-open functionality as an improvement when compared to other PCC builds. This is a breakthrough product and a must-have for law enforcement and civilian gun enthusiasts alike.

Lightweight With Ergonomic Design

The Stern Defense Mag-AD9 adapter is constructed from 6061-T6 aluminum with a 4140 steel NiB coated feed ramp and is designed to be used with a Glock cut bolt. It’s lightweight with an ergonomic design and a perfect option if you are looking to convert a standard AR to use a 9mm or .40 caliber.


  • This magazine adapter must be used with a 5.4 oz buffer or heavier when using a carbine spring.
  • These adapters require the use of a 9mm or 40S&W barrel, “depending on chosen caliber” and a Glock cut bolt.


  • 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
  • Made in the U.S.A.

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

Stern Defense Warranty

Stern Defense offers you a warranty against defects in original materials and workmanship. If your Stern Defense product contains such defects, Stern Defense will take necessary actions to repair, or replace your product. Be sure to retain your original order number as proof of purchase when making a claim.

What the warranty covers

Stern Defense LLC products are warranted against defective materials and workmanship for 1 year from the date of purchase to the original purchaser. Stern Defense’s commitment to this warranty will be limited to, repairing or replacing products upon inspection and (at its discretion) found to be defective in material or workmanship. This warranty is limited and does not extend to improper handling, unauthorized changes or modifications, misuse, abuse, excessive or senseless use, ordinary wear and tear, corrosion, or obstructions.

The solutions provided by this warranty only extend to the original purchaser.

What we do not cover

The warranty in this agreement is the only exclusive warranty related to the product. Stern Defense rejects any warranty express or implied, including but not limited to, warranty of worth or use for a specific purpose. Stern Defense, shall not be responsible for any damages resulting from any means, without limitations, delay cost, lost profits, regarding financial loss or injury to property or to third parties

How to return your item

  • You have 1 year to return an item from the date you received it.
  • Your item needs to have the receipt or proof of purchase containing the order number.
  • Please contact us and send us a message.
  • Please include your order number, name and what is wrong with the product.
  • Merchandise must be return-shipped in a protective box

Contact Details:

  • Phone: 417-932-1128
  • Email:
  • Return Address: Stern Defense, 20780 Suite A State Route JJ,  Summersville, MO 65571

Disclaimer: Manufacturer’s Warranty is subject to change without prior notice.