Archived Posts » 59,672,804
Gemtech UMP issue on USC to UMP Conversion.
2/28/2012 6:09:26 AM
I have an H&K USC which is converted to a registered SBR "UMP" using a Top Notch conversion, and Top Notch Barrel. The barrel has the notched flange, same as the standard HK Barrel. I bought a Gemtech UMP Suppressor, and am currently waiting for the transfer paperwork to return from the ATF (I figure I have about 6-8 weeks left). Anyway, I took my USC/UMP to my dealer to visit the suppressor and try it on, and I could not get it to fit. I dont know the exact specs of the HK Barrel Profile to that of the one from Top Notch, but it appears to be slightly outside of tolerances. I have toyed with the idea of having my dealer (who is also a skilled gunsmith with a great lathe) trim down the barrel (which would cost about $50-80). I also priced a Genuine HK UMP45 Barrel (which would cost about $275). But, before I did either, I was curious if anyone knew anything about the exact exterior dimensions of the flange portion of the two barrels and how they compare. Would I be able to trim down the one I have? Will the HK barrel be a better option and worth the money? I realize that choosing one option does not preclude my ability to go back and try the other.
2/28/2012 9:37:45 AM
IIRC, people have had issues with genuine HK barrels and the flange being out of spec.
The HK barrel is, imo, always going to be better (after that I'd go HDPS). But for cans, I personally will probably have the flange for "looks" and then get the area in front of it threaded.
The HK barrel is, imo, always going to be better (after that I'd go HDPS). But for cans, I personally will probably have the flange for "looks" and then get the area in front of it threaded.
2/28/2012 2:39:23 PM
I have a factory barrel, and the first time I installed the Gemtech, I had to hammer the latch into place. Gemtech blames HK for their "loose tolerances", but I'm pretty suspicious of that claim.
2/28/2012 5:12:10 PM
Unfortunately, a twist off is out of the question at this point, since I already have the Gemtech UMP.
As for hammering the latch....the suppressor doesn't go on nearly that far.
As for hammering the latch....the suppressor doesn't go on nearly that far.
2/28/2012 6:12:15 PM
That's pretty bad then. If you can, opt for a factory barrel. It's probably the easiest way to minimize any problems with the Gemtech.
2/29/2012 12:03:36 PM
Originally Posted By FlyingNut:
I have a factory barrel, and the first time I installed the Gemtech, I had to hammer the latch into place. Gemtech blames HK for their "loose tolerances", but I'm pretty suspicious of that claim.
I have a factory barrel, and the first time I installed the Gemtech, I had to hammer the latch into place. Gemtech blames HK for their "loose tolerances", but I'm pretty suspicious of that claim.
People with AAC cans had similar problems, IIRC.
