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MP-40 barrel nut torque


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#1 Junkhunter

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Posted 29 December 2017 - 09:15 PM

I have my used replacement WW2 German barrel assembly ready to go. How tight to torque the nut down? More then the finger tight my old barrel Was? Any pitfalls to watch out for?
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#2 Black River Militaria CII

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Posted 30 December 2017 - 06:54 AM

If you are looking for an actual torque setting there isn’t one since each gun’s parts fit together differently. Tightness should be sufficient to keep it from loosening when shooting. Some MP40s that I’ve had in the shop had the nut tightened enough so that I had to make a couple special tools and special clamp to hold the receiver, use heat and oil to get the nut off. The receivers of these guns can take a lot of torque without twisting and deforming, but most owners anchor the receiver to unscrew the nut by torqueing against the magwell. The magwell is pinned onto the tube with one pin and if used as a counter to unscrewing the nut, the pin holes will enlarge and the magwell become loose. Torquing against the front sling loop can deform the loop.
So, if you have a safe way of anchoring the receiver, tighten the nut snuggly and see if it loosens up. If it does, clean the threads of the nut and the receiver and use a drop or two of loctite and snug it up again to where it was before. Hope this helps.
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#3 Junkhunter

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Posted 30 December 2017 - 01:41 PM

Perfect. Thank You
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#4 Junkhunter

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Posted 30 December 2017 - 10:52 PM

I put it in my gun cleaning vice locked the rear in locked the front sight block in and torqued it the best I could. If it loosens ill move to the blue loctite if that loosens ill dab the green loctite on.
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#5 El Duce

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Posted 06 July 2019 - 02:02 PM

Loosening is a current problem that I have with mine.   I may have to use the lock tight on it to keep it on.   I thought that I had it pretty tight.   But, yesterday while shooting.  The nut became finger loose.  

 

Any other ideas?


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#6 El Duce

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Posted 08 July 2019 - 05:25 PM

Does  the lock tight method make it difficult to remove the nut in the future?


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#7 1gewehr

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Posted 08 July 2019 - 07:14 PM

A little heat and the LocTite will loosen right up!


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#8 El Duce

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Posted 09 July 2019 - 04:11 PM

Does that include heat from firing the gun as well?   Just curious about how many rounds it would take to melt the lock tight.  


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#9 TSMGguy

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Posted 12 July 2019 - 08:58 AM

Here's a pic of the factory installed staked locking ring on my '41 bnz MP-40. The barrel nut has never been removed. Have no idea what torque value was originally used, but it shows no sign of loosening on its own after 78 years. The sling ring wiggles slightly.

Attached Files


Edited by TSMGguy, 12 July 2019 - 09:00 AM.

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#10 El Duce

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Posted 14 July 2019 - 06:17 AM

Thank you TSMGguy.   I have tightened the nut as best as I can, but it likes to get loose.    I bought a NOS ring and will try that.   Now, I may have to go look, buy my sling ring may be facing the wrong way!   If that's the case.   It came that way when I bought it 10 years ago!!


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