With Unseen Killer’s help, I was able to determine that my Franken 9 problems were entirely due to using printed Sten mags. There was a different problem that affects only milsurp mags, but that’s fixed in UK’s latest drop. If you’re using milsurp mags, print the latest frame and you should be good to go.

The problem with printed mags is that the dimensions deviate significantly from production magazine drawings. Every design I checked was wider at the feed lips and flared more steeply than specs call for. Most are also about 1mm shorter font-to-back. As a result, they won’t seat deep enough to reach the mag catch or feed correctly (or at all). To be clear, there’s nothing the Franken 9 can do to fix this – the incompatibility is with the Glock slide itself.

I didn’t want to print new mags just for this build, but curiosity got the best of me. I remixed a “spec-ish” version of the DMB Sten v1.1 and squirted a test print in PLA Pro. With that the Franken 9 is able to feed 100% reliably in dummy round function testing. I haven’t been able to range test yet, but if that goes well, I’ll post my spec-ish Sten mag remix for anyone that wants a non-milsurp option.

    • Kopsis@forum.guncadindex.comOPEnglish
      3·
      1 month ago

      This is still the v1.1 (Fixed) version, but I reviewed the v1.5 changes and it should definitely fix the milsurp magazine fitment issues. None of the existing printed mag designs (that I know of) will work in any version. My build only works with my redesigned printed Sten mag.

      If you have v1.1 printed and want to verify that v1.5 will work with your milsurp mags before you print it, you can simply use a Dremel to make these v1.5 pockets in the side of the magwell:

      If you want to use printed mags, you’ll need my magazine design (which I hope to release next week).

      • pv2025@forum.guncadindex.comEnglish
        1·
        1 month ago

        yeah… still using printed mags… usk sten mags…

        until all this is worked out community wide, for these style of ‘hammer’ builds iil just stick to the 3011 and recession ruger families.

        • Kopsis@forum.guncadindex.comOPEnglish
          1·
          1 month ago

          Unfortunately, those mags will never work as-is in this design (even Unseen is using milsurp mags instead of printed mags). I’ve been able to run a dozen rounds with my remixed mag just to confirm function, but I didn’t push it any farther because this is still a v1.0 frame with a custom part glued in to fix the guide rod stop problem :) I’m remixing v1.5 with an alternate rear mag catch and once I get that printed I’ll do some more thorough testing on the mag respin to see how it holds up.

    • Kopsis@forum.guncadindex.comOPEnglish
      2·
      1 month ago

      Thanks! Usually when I give up it lasts about a day :) I gave up on my Urutau build at least three times and now it’s one of my favorites.