Micro UZI barrel out of spec problems?

[Redhed]

So, kept thinking for a recent few casual range trips that my Micro UZI/Pro didn’t work well suppressed. Turns out, the threaded barrel I was using looks to be too short/out of spec. Anyone else run into this? Barrel came from RTG Parts a few years ago (and UZI barrels disappeared from everywhere during COVID and never returned). RTG is cool and I’ve gotten a lot of good stuff there, but both Uzi barrels I’ve tried from them didn’t work. I’m sure some machine shop was doing them for them, but maybe not too well.

 

[Jones]

Threaded section does appear short but the rule of thumb is that usually run (length) of the threads should be as long or longer than OD of the threads.
Screw device, on part way and see if you have any wobble. That'll show if the threads are undersized.
Screwed all the way on; what is the device supposed to seat on? Barrel nut, bottom out on the end of internal threads... ?
I'd suspect the first possibility is the most likely. Does the device loosen up while shooting? Another undersized threads clue.

 

[Redhed]

I think the problem lies in the distance between the shelf that sits in the Uzi receiver and the chamber end of the barrel. It’s like 1/16” shorter than the factory barrel. Extractor sometimes cannot grab the case heads. Headspace way off.

 

[Jones]

Here's my factory barrel, dimensioned.

 

[barrelxchange]

I make those barrels but do not do threading for suppressors.

 

[Redhed]

Hi barrelexchange! I have an UZI handguard rail from you. So, are you saying you made these barrels for RTG?

I don’t believe there are any problems with the 1/2x28” threads on the muzzle, the problem seems to be behind the collar where if you add up the measurements on Jones image above - .120 + .570 + 2.205 + .320 = 3.215. But as you can see on my barrel that same portion comes in at 3.1560. So the headspace is wrong, will fire sometimes, but sometimes the extractor can’t grab the cartridge rim.

Check out my other images above, you can see it’s shorter than the factory barrel.

 

[barrelxchange]

I do not make them for RTG or any other vendor. I just make them to order for customers.

You are correct the length from the locking collar to rear of barrel is too short (headspace).
I think I have a standard length 9mm pistol barrel in stock.

Troy

 

[Redhed]

Should have asked you first apparently! Email sent to your AOL address Barrelexchange. Fill me in on the options. Thanks!