M44 tight chamber.

Unscrewing the barrel wouldn't be the fix if that was the issue.

Are you sure that it's still chambered in 7.62x54R?

If the chamber is undersized, you'd use a reamer to cut the chamber deeper.

gotboostvr said:

Unscrewing the barrel wouldn't be the fix if that was the issue.

Are you sure that it's still chambered in 7.62x54R?

If the chamber is undersized, you'd use a reamer to cut the chamber deeper.

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I'm fairly sure that 7.62x54R headspaces off the rim, in which case stoning the face of the bolt would work. You'd want a Go gauge to set it, the gauge looks like a coin:

https://www.amazon.com/Mosin-Nagant-Headspace-Gauge-Firewerks/dp/B0088AEZJG/ref=pd_sim_1

BSW

If its anything like a mauser barrel, it could be shimmed. Cant recall if theres anything besides sights on a mosin that need to be timed with the barrel threads, like an extractor cut. I didnt want to wait for a reamer on a 6.5x55 mauser project that had the exact same problem you described. I cut what is basically a paper thin washer out of .004 precision ground stainless shim stock and re-installed the barrel with the washer between the barrel and action. No different than installing the recoil lug on a remington 700 but on a much smaller level. Worked like a charm. This would of course move your sights out of line.

The mosin barrel has some interesting cuts on the back for the extractor.
Wrenching on it will make it a club, due to the extractor not being allowed to work.

Start with a chamber casting before doing anything.

Then see if you can get a bore scope or enough light to inspect the condition of the chamber.

Take some photos of the entire rifle, the receiver and barrel markings and some showing the fit of the barrel to the stock, Post here for the collective wisdom of the group.

Check your headspace, the gauge is not overly expensive, perhaps someone on here will have one you can borrow. The Mosin uses a bolt with a separate bolt head. I'm guessing yours was removed and replaced with one "too tight." Swapping a bolt head will likely fix the issue if you find one that's "looser."

Do the numbers struck on your bolt head (if any) match the bolt body and receiver?

Tight chamber? Have you done a detail strip and cleaning to get all old cosmoline out of the chamber? Take the barreled action out of the stock and set it into a plastic tub filled with mineral spirits for a day or two, scrub every few hours with a chamber brush. Pretty much guaranty this will fix your issue. Hopefully you didnt create excess headspace with your bolt sanding.

I'm guessing that you either have a mis-matched bolt as noted in #7 OR it's an issue as noted in #8.

Before addressing anymore metal - determine which of those two potential sources you have.

Todd.

illinoisburt said:

Tight chamber? Have you done a detail strip and cleaning to get all old cosmoline out of the chamber? Take the barreled action out of the stock and set it into a plastic tub filled with mineral spirits for a day or two, scrub every few hours with a chamber brush. Pretty much guaranty this will fix your issue. Hopefully you didnt create excess headspace with your bolt sanding.

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Ditto. I've had this issue. It was the result of a dirty chamber. In addition to cleaning & scrubbing per above you might also want to try Flitzing (cleaning well after, natch).

Most likely the two pieces of the bolt aren’t original.

When fixing a problem start with small solutions and work your way up. Start with a good cleaning. As @wiscoaster mentioned, and then go from there. If that doesn’t fix the problem I’d be willing to bet if you bought a new bolt face or new bolt altogether your problem wouldn’t be so problematic.

SamT1 said:

It’s all matching numbers. But they are electro pencil too.

I’ve not done any extensive cleaning. I figure I put a lot of rounds through it before it ever got cleaned circa 2003.

the bolt hasn’t been modified yet. I just modified some reloading brass to work.

gun shoots about a quarter size group. I’ve done lots of trigger work on it too.

I’ll start with cleaning it good.

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That's the way to go. Cosmoline is a wonderful preservative and a horrible lubricant. It dries almost like a varnish which normally it will not work itself out over time. Only choices are mechanical removal with either heat or chemicals. What you are experiencing is very likely the infamous Mosin Sticky Bolt. This is super common though with fewer 'new' surplus flowing in people kind of forget.

Yes give the chamber a good scrubbing. Besides dried cosmo the steel cases are lacquer coated and this can build up on the chamber walls causing hard chambering and extraction.