Stern Defense MAG-AD-MP9&40 Magazine Adapter for AR15

Stern Defense MAG-AD-MP9&40 Magazine Adapter for AR15

  • $190.00
  • Save $9.99

Convert your standard mil spec AR 15, M4, M16 lower assembly to use 9mm and .40 S&W M&P 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-AD 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

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

CLICK HERE for Install Video:


Older Generation Glock Magazine 2004 and Prior and Aftermarket

Will it work with this magazine?

Although the MAG-AD9 works with many aftermarket magazines, we recommend using post 2004 square notch, Glock OEM magazines. As these will provide the best fit and function.




Please note the above picture, notice the lack of a ledge on the new magazine as compared to the old. Also please note the (SQUARE) shaped notch on the new magazine as compared to the (U) shaped notch on the far right magazine.

(U NOTCH) magazines are very early generation glock magazines, they were not fully metal lined and due to this they expand when loaded causing reliability and insertion issues. 

2004 and prior magazines (SQUARE and U-NOTCH) also contain a ledge on the right hand side as noted by the above picture. 

While in some situations these magazines can still be used with the MAG-AD9 series, they may require more force to seat the magazine or may not seat at all. Some very light modification can be done to the magazines to allow them to seat easier.  

We still do not recommend the use of U-Notch magazines, as even with modification, they may not work or be reliable due to the lack of a full metal liner and expansion when loaded. 

If you want to use these types of magazines, you can slightly modify the magazine in order to fit. See figures 1 and 2 below.


Figure 1


If you have these older magazines and wish to use them. Please note the areas of the magazines that will need modification .  

Figure 2

If you wish to use these magazines, you can take a simple household file and bevel the indicated edges slightly ( green arrows as shown in figure 2.) This will allow the magazine to seat fully without excessive pressure. This should be done in small increments with test fitting and should not affect the use of the magazine in Glock pistols. DO NOT MODIFY THE AREA INDICATED BY THE RED BOX. 

While we have experimented with this and have had zero issues. Stern Defense accepts no liability for modifications you make to your magazines, If you decide to do this you do so at your own risk.  

Will it work with my lower?

The MAG-AD9 will not function properly on mag wells with irregular contours, "3D skulls, waves, and other non mil-spec contours."

NOT recommended for non mil spec billet lowers.   

For the best experience, please use the MAG-AD9 with ar-15 and m16 mil-spec lower receivers.

If you have a billet lower please see the guide below 
to further assist with compatibility troubleshooting. 

(The picture below shows a lower that is compatible.)

Please place a scale on your lower perpendicular to the top of the lower, (indicated by a green line with an arrow.) The edge of the scale should run tangent to the radius indicated in red as shown.   The final point of the scale should rest on the bottom of the magwell. The distance across this point should not exceed 2 & 13/32 inches. or 2.406 inches.
 Will it work with my upper? 

The MAG-AD9 is designed to be used with ar-15 and m16 mil-spec upper receivers.

Bolt Compatibility?

Recent development, the MAG-AD9 system is not compatible with PSA Hybrid or Foxtrot Mike bolts. This is due to the lug which strips a round off of the magazine being .035 of an inch further from center-line as compared to other bolt systems.


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