Mosin Nagant bolt groups interchangable?

This won't affect headspace, as long as the bolts arent ridiculously worn out. Headspace is a match between barrel and receiver, bolts have little affect on this. Swap away...

Headspace is a match between barrel and receiver, bolts have little affect on this

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Thats not true.
With a rimmed caliber like the 7.62x54R, headspace is a match between the breechface of the barrel and the bolt face.

With any rimless caliber, headspace is a match between the chamber shoulder and the bolt face.

Where the bolt locks into the receiver can have a profound effect on that.
And different bolts may or may not lock in the same relationship with the breechface due to wear, lug set-back inside the receiver, or different specs on two different bolts made years apart.

Whether or not all Mosin bolts were exactly the same over the 54 years it was produced is open to speculation. My guess is they are not.

Use a headspace gage to check it if you swap bolts.

Here is a good read on it:
http://www.russian-mosin-nagant.com/headspace.htm

rc

Thats not true. With a rimmed caliber like the 7.62x54R, headspace is a match between the breechface of the barrel and the bolt face.

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It's not entirely false either, a barrel set too far back it wont close, and too far forward the headspace will be too great and dangerous to fire. After reading the link RC put it up it does make sense to get it headspaced first...

If the bolt is hard to close, afte changeing bolt heads, its a bit tight, if the cartride shakes adibly, its a bit loos, but the critical point is the Rim space, where the headspace is mesured. Its mesurement is standard on the ammo and the bolt heads.

99% of all Mosin Bolt heads will exchange, no problem, but theres always a few worn out ones, as they were made by humans and all thier inherent faults.

They make a simple gauge, so while its not a concern, its is checkable , for safety sake.

Zebras

The odds that hoofbeats outside your window are caused by zebras is pretty slim, but there is always a minuscule probability (circus train derails, clowns try to escape on zebras... ). The odds that a Mosin will blow up after I switch bolts is enormous; don't put yourself in my place...

D'uh.

Assuming that they were each properly headspaced to start with, take the bolt head or face from the rifle you intend to be the one you use, and the bolt body from the other rifle, if this is what you choose, and assemble them.

The headspace is determined by that little bolt head with the extractor claw in it, not the bolt body or the striker. If you use the same bolt head (the part with the extractor) from the rifle it was properly headspaced from, you should be good to go.

HTH.

I'm sure there were a lot of battlefield parts swaps I wouldn't worry about it too much.

Strange, then, how everybody gets in a fluster with Lee-Enfields about this same issue.

kd7nqb said:

I'm sure there were a lot of battlefield parts swaps I wouldn't worry about it too much.

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It's a different matter when people are actively shooting at you vs wanting to spend an afternoon at the range...

OP: the bolt head is the part that matters for headspace. That's the bit with the extractor claw and the two ears that locks into the receiver. You can swap everything else, just keep the bolt head matched to the rifle it came with. Be sure to check firing pin protrusion afterwards.

I have four Mosins: a 1915 White Westinghouse, a 1936 Izzy, a '39 Tula and a '44 Izzy. Just on a lark one day, I removed all the extractors and dug out my no-go gauge and started checking headspace, and then swapping bolt assemblies and checking again. Sure enough, they were all within spec, there was no noticeable difference at all in fact. Nice to know. Just wanted to throw my two cents in.

Very common, actually uncommon not to have markings...

Depending upon who the importer was and when it was imported, markings could be anywhere if at all.

A couple of importers were really good at putting their stamp out of the way under furniture but the feds put a stop to that. Also they ended the practice of the lightly struck micro stamps which were hard to see in the first place and easily removed if bothersome. My SKS has one of these which presents more as a minor blemish than anything else.

Headspace is the difference between the face of the bolt HEAD and the back of the chamber. The head is a separate part. The 54R is very tolerant of chamber variations but it does need to have a proper rim fit. Most of the time you can get away with swapping bolts but you should check headspace to be sure.

Or you can just follow stubbicatt's solution.

Orion8472 said:

I will give it a good look over tonight. If it doesn't have any importation etchings on it, does that make it more valuable, or just more rare and a conversation piece?

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I don't think the importers were required to mark their guns until after the GCA of 1968. I have a couple of surplus guns bought prior to 1968 with no markings.

Import marks used to be placed toward the end of the barrel. If not on the receiver, that's the next place to look.