Firearms,  Shooting Sports

GS Designs – AR Magzine Extension Review

Made For Canada!

Words by: Wally F.          Photos by: Wally F.

Editors note: First published in the Canadian Firearms Journal for their September issue.  This is that article with updates at the end.

          A concept so simple I’m shocked that it hasn’t been done this way before now. A simple base plate replacement of a ten round LAR-15 pistol magazine or Mission First Tactical (MFT) ten round AR pistol magazine with a polymer base extension that mimics the dimensions of a full sized AR magazine. Having plenty of both MFT and the ubiquitous aluminum stamped LAR-15magazines on hand this would be a good hard test run for these magazine extensions by GS Designs.

Two MFT Extensions in the foreground and a LAR15 extension in the rear.

          The attachment of the extensions for the aluminum magazines was very straight forward,slide the base plate off, slide the extension in it’s place. There is an upward curve on the back of the extension that acts as a natural back stop so you’ll never over insert the magazine to far to the rear. On the front side is a solid Philips screw that turns into the polymer extension to keep the magazine from shaking forward and loose with repetitive impact and use. The MFT magazine was similar but both the extension and base plate are held into place via dual notches first at the bottom of the MFT magazine which is replicated again on the bottom of the extension to secure the base plate on.

MFT and LAR-15 magazines extensions side by side.

          Over 3 months of testing the magazines here is what I’ve learned. Both designs mimic the size and handling of regular sized AR magazines, but with the benefit of ten rounds instead of five. This is a huge advantage to 3-Gun competitors, many of which I know use these magazine extensions regularly. I could have cheated and just done dry magazine dumps but I elected to load and fire rounds as well so that spring pressure, weight, recoil stress,as well as the actual drops are all factored in.

Load your magazines as if they were standard sized magazines.

          The first 30 drops between two sets of the MFT and aluminum extensions were on a concrete floor at an outdoor range, encountering no issues with feeding rounds into the chamber or loading. Magazines dropped free with no issues. The next 40-50 drops were done at an indoor range three weeks later where the floors had rubberized mats. This is where the MFT extension on one of the magazines cracked along the top where it is thinnest in the notch. Other users in the community have mentioned this issue before where their MFT extensions have exploded on contact with gravel in the middle of a 3-Gun match. No explosion here just a crack, on a rubber mat of all things. Two weeks later another 50 drops were conducted at another outdoor range on to gravel. I ran the same cracked MFT magazine and it surprisingly has still held up. I briefly toyed with hockey tape or crazy glue but left it to see what would happen. So far so good. The aluminum polymer extensions ran flawlessly with well over 130+ drops and counting.

Minor crack on this first gen extension at the lip.

          The aluminum extensions designs perfectly line up with the classic design of a regular sized AR magazine, where the MFT extension is somewhere between the windowed style of a MagPul magazine and something else. Both are functional and I highly recommend the extensions for aluminum LAR pistol magazines. If there is a way for GS Designs to toughen up the one little weak point on their MFT magazine extensions I’d personally go buy more of them as I like the grip and texture better than the traditional aluminum design. Find out more at HTTP://

The visual cues from both the LAR-15 and MFT extensions line up with their respective magazines.

UPDATE: Since the original publishing of this article the team at GS Designs has refined the extensions to be much more reliable on drops with better texturing and a rainbow of colour choices.  I am still seeing scores of shooters especially in the 3-Gun community still using these extensions aplenty.  With an affordable price point on these magazine extensions there’s no reason why you wouldn’t want to add these to your 10-rounders.

Aggressive grip notches on the spine of the MFT extension.

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Reporting for TV-PressPass

Wally F.

Staff Writer and Reporter for TVPP. Background in Broadcast News Operations, Journalism, Criminology, and Firearms. An Infantry NCO for over fifteen years in the Canadian Army and still counting. Spent 8 months in Iraq working on my tan. I love my country, family, brother-in-arms, shooting sports, and positive responsible promotion of firearms and everything that surrounds it in Canada and beyond.