Mosin-nagant heavy bolt lift

[bob4wd]

I've got a bunch of mosins, and am trying to make at least one of them into a decent shooter. Seems that the best looking one has the heaviest bolt lift, and the biggest dog cocks like a well-tuned model 70. Tried the obvious, swapping out mainsprings, which had no effect, swapped bolts and the easy-cocking one stayed that way, and vice-versa. So the difference is in the bolt, which makes sense. But not the mainspring? I hesitate to swap bolts around, assuming that the importer fitted the correct headspace bolt when they were assembled. Maybe not.
So-any ideas on how to reduce the (sometimes excessive) heavy cocking effort?

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[jmoore]

Swap bolt bodies but leave the bolt head with the rifle from which it came, if you are concerned. It's not too likely a US importer would have checked headspace. Other countries aren't generally as lax. Quite frankly, It doesn't seem to be a big issue with these rifles.

[bob4wd]

Swap bolt bodies but leave the bolt head with the rifle from which it came, if you are concerned. It's not too likely a US importer would have checked headspace. Other countries aren't generally as lax. Quite frankly, It doesn't seem to be a big issue with these rifles.

Good idea, I agree that headspace is probably not checked by the importer, but you never know. A more important problem that I didn't mention at all is that the two best ones are also all-matching andhave by far the heaviest bolt-lift of all of 'em, so don't really want to swap bolt bodies. Any more good ideas, like maybe shortening the main spring?

[jmoore]

It's in the cams, not the springs. You need plenty of mainspring pressure to accelerate the heavy striker enough to detonate the primer. It's an energy rather than a momentum dependent function.

If swapping bolt bodies, at least temporarily, improves function, then the cause is likely a rough extraction or cocking cam surface on the bolt body. Check the inclined surfaces and lightly stone smooth the rough places. Some Prussian Blue might help show the affected contact surfaces.

[bob4wd]

Yeah, I figured it had to be cam angles or some such. I guess it stands to reason with war-time tolerances and all. I noticed that a bunch of post-war M44s were much smoother and easier to operate. Anyway, good input and I'll go from there. Thanks.

[barbarossa]

Bob4wd, there's another way to skin the cat that does not involve tring to polish out the cam surfaces. Now, all I did was disassemble all of my Nagant bolts and then laid out in the cocking pieces/strikers and installed them one at a time on the bolt body in question and tried them for smoothness in the action. This worked amazingly well and produced a cocking piece which worked well with my bolt body. I think the Russians may have done the same as Colt and Smith&Wesson did back in the old days. Sit there with a bin full of cocking pieces and install them til you come up with a good smooth operating assembly.

[bob4wd]

Bob4wd, there's another way to skin the cat that does not involve tring to polish out the cam surfaces. Now, all I did was disassemble all of my Nagant bolts and then laid out in the cocking pieces/strikers and installed them one at a time on the bolt body in question and tried them for smoothness in the action. This worked amazingly well and produced a cocking piece which worked well with my bolt body. I think the Russians may have done the same as Colt and Smith&Wesson did back in the old days. Sit there with a bin full of cocking pieces and install them til you come up with a good smooth operating assembly.

Good idea- i actually started doing the same thing myself, but got lazy andjust went with the rifle thathad the best feel as-is. Took it (a non-import m44) out tothe range last weekend, but not real accurate, so will probably have to do the bolt body swap thing after all. I've got a bunch of 'em so might take awhile- (sounds like you do, too). We'll see.

[INLAND44]

Mine cocked fine until I fired a few rounds which is when the bolt got stiff, and I had to smack the handle to turn it. This is very common with the MN, and while it may have something to do with the causes mentioned above, most of the time it simply is an invisible build-up of casing lacquer in the chamber. You'll have to use shotgun cleaner (plastic solvent) on the appropiately-sized brush for the chamber and spin it with a drill. Just be careful to not damage the leade area of the rifling. The more-worn examples have loosened up and the locking lugs have polished from use which is why they are smoother. I would not mess around with swapping bolt parts or polishing anything - the gun will 'come-in' with use and adequate cleaning/lubing. If the bolt numbers do not match, you must insure correct headspacing before firing. My 1953 Hungarian M44 had an older Tula bolt so I bought a set of gauges - the thing turned out perfect!