My friend Brian M. sent this picture to me. He and I always like higher capacity especially for USPSA and 3Gun. Around the same time as my Scorpion Evo3 +10 extension, Brian had the idea to make an extension for Colt/UZI SMG magazines. It is a +8rd extension making the Colt/UZI mag hold 40rds of 9mm. He drew this up and 3D printed it in his home. He successfully tested it fed all 40 rds.

9mm ARs are becoming increasingly popular. Sure you can get some that use Glock magazines but there are still a lot of guns out there using the Colt/UZI pattern magazines. I see these becoming very useful and not in just AR-9 but in 9mm Tavors or any other 9mm carbine that uses UZI mags.


  • c4v3man

    Any chance of a link to the 3d files for these?

    • Blackhawk

      Sorry, the government won’t let you get the files. But trust them, it’s for your own safety…

      • Blake

        Uh what? The government is not involved at all, and all kinds of magazine extension .STLs are available all over the internet.

        • Blackhawk

          It was a joke, based on the government demanding previous files be taken down…

    • JSmath

      I feel the reason it won’t get posted is that the moochers who just copy the file will have unreasonable expectations, and the day they drop and break their extension(s), they’ll come crying with a salvo of complaints that the creator will have no desire to deal with.

      • c4v3man

        Come crying to who? You print it, it’s your problem. It’s entirely different from someone selling you a 3d printed object that is pre-printed, then hell yes I expect support for the physical product I bought. But a design is just that, and any breakages or issues could just as easily be a problem with the way your printer is configured, the materials you’ve used to print, or a myriad of other factors.

        • JSmath

          You appear to be blessed with common sense. Many individuals, especially those who find themselves downloading things off the internet without ever creating things for others or themselves, tend to lack it. Printer and material selection should be everyone’s first asumption, but I’ve seen people jump to blame fault on the designs they’ve merely stolen off the internet firsthand and it’s more than a little annoying if not disgusting.

      • Nicholas C

        Actually that is not it. This is like asking someone for free stuff. He worked hard to design this and all you gotta do is print it out? It is like asking for free copies of digital music or books.

        • JSmath

          Yet people give their music and writing away for free on the internet all the time… It’s when people steal their work and especially sell it for profit that those artists and creators turn away from sharing. Happens all the time.

          There is a distinct likeliness (certainty) your friend borrowed design cues and or specs from others to make his little mod come together. Not judging, just stating.

  • Jeff Smith

    Just curious: how strong is the plastic used in 3D printers these days? I remember hearing that it was rather brittle at one point. How would these do in a drop test? Or how would the ears of the extension (that slide over the base of the mag) stand up to the spring pressure and bumps/accidental hits?

    • Mark4931

      It depends what material you are printing with. Newer polymers handle impact fairly well, but can lack durability. Good design will minimize stress points to reduce cracking.

    • Stephen Paraski

      you can now get a mixture that is part carbon fiber pellets, for those large scale printers. Wait 6 months and it will be on a spool.