Help needed to identify particular USM1

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   just coming back from the shooting range.
Result is quite satisfying but some cartridges do not allow the bolt to close completly. 
Shells are 2nd use, reloaded and resized.
All of them are slicing well into the chamber but some seems to be slighly oversized at the bottom.

Did you ever experienced it and how to solve ?

Thanks 

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Atok91 Members Profile Send Private Message Find Members Posts Add to Buddy List Recruit Joined: Dec 02 2021 Location: France Status: Offline Points: 17	Post Options Post Reply Quote Atok91 Report Post Thanks(0) Quote Reply Posted: Dec 04 2021 at 12:27pm
	just coming back from the shooting range. Result is quite satisfying but some cartridges do not allow the bolt to close completly. Shells are 2nd use, reloaded and resized. All of them are slicing well into the chamber but some seems to be slighly oversized at the bottom. Did you ever experienced it and how to solve ? Thanks

Atok91 Members Profile Send Private Message Find Members Posts Add to Buddy List Recruit Joined: Dec 02 2021 Location: France Status: Offline Points: 17	Post Options Post Reply Quote Atok91 Report Post Thanks(0) Quote Reply Posted: Dec 04 2021 at 12:49pm
	Even After passing through sizing die (without decapping pin of course...), Bad cases still don't allow the bolt to close No "Factory crimp die" used at the moment

floydthecat Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Oct 13 2016 Location: Mississippi Status: Offline Points: 2307	Post Options Post Reply Quote floydthecat Report Post Thanks(0) Quote Reply Posted: Dec 04 2021 at 3:14pm
	The first thing one should usually do to any freshly acquired carbine is check the head space. It might be tight, but allow cases a little shorter to chamber. Plating, especially early plating, can add material to contact surfaces that establish proper head space. We are talking about thousandths of an inch, which really can matter. It is also possible the chamber could have been plated to some degree as well, which might require a finish reamer to correct. One can check head space without gauges.

Atok91 Members Profile Send Private Message Find Members Posts Add to Buddy List Recruit Joined: Dec 02 2021 Location: France Status: Offline Points: 17	Post Options Post Reply Quote Atok91 Report Post Thanks(1) Quote Reply Posted: Dec 04 2021 at 4:24pm
	Seems I found the root cause. Case length was exceeding recommanded value 32.77mm. (found case length 32.90mm) After cutting, works fine :)

floydthecat Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Oct 13 2016 Location: Mississippi Status: Offline Points: 2307	Post Options Post Reply Quote floydthecat Report Post Thanks(0) Quote Reply Posted: Dec 04 2021 at 4:50pm
	32.90 mm would equate to a tad over 1.295-inches, if my math is correct. 1.295-inches is the usual no-go gauge length. Sounds like you have a nice tight action.

Atok91 Members Profile Send Private Message Find Members Posts Add to Buddy List Recruit Joined: Dec 02 2021 Location: France Status: Offline Points: 17	Post Options Post Reply Quote Atok91 Report Post Thanks(0) Quote Reply Posted: Aug 08 2025 at 7:40am
	Hello. I finally took the time to complete the datasheet with every detailled pieces. Where can I send it to have a feedback on it ? Thanks in advance

W5USMC Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: Apr 29 2017 Location: Missouri Status: Offline Points: 3640	Post Options Post Reply Quote W5USMC Report Post Thanks(0) Quote Reply Posted: Aug 08 2025 at 10:01am
	It would be great if you posted a picture of the data sheet here on this thread in addition to emailing it to DataSheet@UScarbineCal30.com
	Wayne USMC Retired NRA Life Member

Atok91 Members Profile Send Private Message Find Members Posts Add to Buddy List Recruit Joined: Dec 02 2021 Location: France Status: Offline Points: 17	Post Options Post Reply Quote Atok91 Report Post Thanks(0) Quote Reply Posted: Aug 08 2025 at 10:46am
	After years, I finally took the time to complète the datasheet for my particular USM1. I'm very interested in your feedback about it's history For exemple, the stock has hand-marked RMC stamp on sling cut and regular UEF GHD stamp below buttplate I appreciate any other historical détails you could learn me about it. Cheers from France and hope to hear from you soon.