MBX AR Basepad Extension and coupler for PMAG Gen 3

Just after my review of the The XMag Coupler from Germany I discovered this solution from MBX Extreme which I think will be of interest.

The system will add both capacity and the possibility to couple a Magpul PMAG to another. There is also a “wing” to lift your rifle if it’s laying flat, and make your pistol grip more accessible.

The basepad itself is 39 USD and comes in black, blue and red.




If you want to connect your magazines, there is a MBX AR Modular Coupling set.

The set includes two MBX AR Basepad Extensions for PMAG (Gen 3) and one MBX Inter-Loc Block, which connects the two.

This solution joins any PMAG Gen 3 together, from 10 to 40 rounds.

You will also get added capacity for both your magazines: 3 Rounds for 20 PMAG, 4 Rounds for 30 PMAG and 5 Rounds for the 40 PMAG.

The Inter-Loc Block itself is 27 USD.

Note: You have to remove the factory plastic lip from the magazine spring, otherwise you will not get the added capacity (and perhaps not the function either).

The installation requires no tools.


As if this “LEGO-style system” was not enough, there’s an MBX Inter-loc Stabilizer Support Set.

This adds support to your basepad extensions, but I think the main advantage may be if you have a stage where your rifle is supposed to lay flat on the table. If the “wing” if the stabilizer lifts the rifle and makes your pistol grip easier to reach, well then you might have gained a few tenths of a second over your competitors.

MBX Inter-loc stabilizers support set gives support to a single or double magazine configuration allowing for an extremely stable monopod platform for the ultimate performance. Also, allowing for staging of a rifle with muzzle up or down while having a single magazine inserted.

Below: “MBX extreme CEO Adrian Cobb goes over the form, function, and unique design aspects of the “New” MBX Inter-Loc AR System.


You can find more details and prices at the MBX Extreme homepage.

Eric B

Ex-Arctic Ranger. Competitive practical shooter and hunter with an European focus. Always ready to increase my collection of modern semi-automatic firearms, optics and sound suppressors. Owning the night would be nice too.


  • FredXDerf

    Too bad they put their name on every visible surface. An annoying trend that most people don’t seem to notice but pretty soon ARs will look like NASCARs with logos all over every part.

    • Flounder

      I think parts should be branded. It is a way to get warrantee service and show that you used quality (or counterfeit) parts. It also reminds you what to look for if you want another of the same part a decade or two later.

      Edit: it is a little heavy here, and the patent pending is a complete and total joke. It really just means they have no patent and absolutely nothing novel going on here. They are just capitalizing on ignorance.

  • Indianasteve

    I agree with Fred’s logo statement. I would much prefer low key, unless they are going to sponsor me. I also am leery of all these mag extenders that keep the original spring. Maybe they will feed all those rounds ok, but I will never count on it when it’s important.

  • Spencerhut

    It’s a competition part. By plastering the MFG name all over it, the owner is saved the hassle of telling every other competitor who made it.

  • Flounder

    So… 39 for one block, 27 for the connector and 39 for another block…

    LOL this is so stupidly expensive… priced. 105?!?!? FOR A MAG COUPLER!!! And all that billet aluminium! I bet it is heavy too!

    Shoot, just looking at that mark up makes me want to go buy myself a mill.

  • Sledgecrowbar

    I get that it’s for 3-gun, but the Strike Industries +5 PMAG extension is $11. Which is still more than the PMAG you attach it to.