Mosin Nagant bolt groups interchangable?


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Orion8472
January 27, 2013, 01:50 PM
Can you swap out the bolt assembly between two Mosin Nagants, or would there be a headspace issue doing so? If I have two M44's [1944 and 1046] and wanted to put all the nice parts in one [and have an extra "lesser" rifle], could that be done?

Thanks.

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Buck Kramer
January 27, 2013, 03:41 PM
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...

Orion8472
January 27, 2013, 03:47 PM
I was kinda thinking that. The numbers of these they put out, and in the quickness required, I couldn't imagine them making a solitary bolt group for a specific rifle. I was thinking that they probably had a bunch and put them together assembly line style. Of course, I don't know if they DID, but I could see it happening that way.

The two bolt groups I have were identical, so I will try it out. Anyway, I put the best stock with the best looking metal and bolt. It has a very shiney bore. The other one's bore is dull and a bit pitted. Still shoots fine, but will use it for when I shoot corrosive rounds [still cleaning it after, of course].

rcmodel
January 27, 2013, 03:50 PM
Headspace is a match between barrel and receiver, bolts have little affect on thisThats 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

Buck Kramer
January 27, 2013, 04:30 PM
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.

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...

caribou
January 27, 2013, 04:52 PM
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.

Maj Dad
January 27, 2013, 04:56 PM
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... :p ). The odds that a Mosin will blow up after I switch bolts is enormous; don't put yourself in my place... :cool:

stubbicatt
January 27, 2013, 05:52 PM
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.

kd7nqb
January 27, 2013, 06:01 PM
I'm sure there were a lot of battlefield parts swaps I wouldn't worry about it too much.

Mk VII
January 27, 2013, 06:13 PM
Strange, then, how everybody gets in a fluster with Lee-Enfields about this same issue.

Caliper_RWVA
January 27, 2013, 10:23 PM
I'm sure there were a lot of battlefield parts swaps I wouldn't worry about it too much.

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.

Orion8472
January 28, 2013, 09:41 AM
Very good posts, guys. I will switch the bolt faces and call it good. :)

So, here's what I had:

M44 #1: Niice original wood and finish, nice looking bolt carrier.

M44 #2: Nice metal, MUCH shiner and clean bore.

So now, M44 #1 has all the nice parts, and I have a second one for most of the shooting.

bainter1212
January 28, 2013, 10:01 AM
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.

Orion8472
January 28, 2013, 12:06 PM
Wow! Over such a relatively large amount of time, being basically the same. Quite interesting. Thanks for your input. :)

Orion8472
January 29, 2013, 09:58 AM
Made the bolt head switch, last night. It was a bit of luck. Internet was down, so I didn't have that advantage of finding a "how to". But saw that the back part of the carrier could be pulled backwards, and by chance, I moved it counter clockwise 1/4, and discovered the key to taking it apart.

Now, I have one pretty nice M44 {made in 1946}, and one "beater" {made in 1944} ["beater" meaning, the one I'll shoot more. . . and run corrosive through, if I choose to use such rounds, since it's bore is already rather pitted and dull].

One thing though. The 1944 rifle has a C.A.I. import etching on the left side of the receiver. The 1946 rifle doesn't seem to have any etchings. Just the normal Russian stampings.

Orion8472
January 29, 2013, 04:30 PM
As for the importer etching. Is that common on these, or rare?

Buck Kramer
January 29, 2013, 08:01 PM
Very common, actually uncommon not to have markings...

Orion8472
January 30, 2013, 09:41 AM
Other than the left part of the receiver, where else would an importer etching be? I will look again on this 1946 rifle, but didn't see one where the 1944 rifle was etched.

ApacheCoTodd
January 30, 2013, 03:50 PM
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.

Orion8472
January 30, 2013, 03:52 PM
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?

Cosmoline
January 30, 2013, 03:55 PM
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
January 30, 2013, 03:59 PM
That's what I did. Switched the bolt heads.

GCBurner
January 30, 2013, 04:04 PM
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?
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.

Orion8472
January 30, 2013, 04:54 PM
I see. Well, it sure looks a lot cleaner without them. :)

Sergei Mosin
January 30, 2013, 05:29 PM
Import marks used to be placed toward the end of the barrel. If not on the receiver, that's the next place to look.

Clark
January 31, 2013, 12:18 AM
Measure a bunch of Mosin Nagant bolt heads.
The seem to be interchangeable... 91/30, M59, or M44, it does not matter.
All within 0.001"


What is NOT interchangeable is barrels and receivers.
The thread clocking is custom.
And it is not just getting the sights to point straight up.
The real problem is extractor relief cuts. For the rim to headspace on the barrel, a tiny more than 180 degrees of no extractor relief cut needs to be there. The 90 degrees of bolt rotation PLUS the width of the extractor all work together to make is a tight fit.

Orion8472
January 31, 2013, 10:04 AM
Thanks Clark for your input here. Good experiment!

I probably really didn't NEED to switch bolt faces, but did so just to be "safer".

To everyone else, . . . I didn't find any import marks. SO glad I got the other M44 in order to make one very nice one. :D

303tom
January 31, 2013, 11:40 AM
I would like to stick my .02 into this fray, while head space is a concern in all firearms, it is not as much of a concern with rimmed cartridges, hence the revolver. With that said, you should ALWAYS check or have checked the head space of said rifle.............

Orion8472
February 1, 2013, 10:08 AM
After discussing this topic with a gunsmith, I am going to take both M44s to a gunsmith to check the headspacing, . . . just to be safe. It is a powerful round, afterall.

bainter1212
February 1, 2013, 10:27 PM
DEFINITELY cheaper to buy the No-Go gauge yourself. A hammer and punch removes the extractor in a few seconds (it's dirty under there, believe me). Insert gauge and try to close bolt. Super simple. Should be about 30 options through Brownells.

Ar180shooter
February 1, 2013, 11:55 PM
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 was thinking the exact same thing.

Orion8472
February 11, 2013, 12:46 PM
As an update, I took both M-44s out to the range, yesterday, and fired two rounds each [using a metal clothes hanger to pull the trigger]. They both operated normal and the casings showed no abnormalities in casing or primers. I can take some shots of the spent casings if you all want to see them.

On a side note, . . . it doesn't take but one round to draw a crowd.

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