More Mosin questions

[wierdscience]

Well after looking around at a few different rifles I managed to pick up a M38 carbine in excellent shape for $100.Pics to come.

It does have one problem,the headspacing seems to be too tight.The action is smooth and easy until about 5* from being locked home when it gets tight.Also the face of the bolt is showing scuff marks along with the cartridge.

Anybody ever deal with this on a Mosin?

[38_Cal]

I would start by making a Cerrosafe chamber cast to verify that there's nothing in the chamber causing the hard closing. If it's ok, then think about lapping/polishing the bolt face very lightly, too much and you'll increase headspace.

[TECHSHOP]

There are several different specs and types of 7.62x54mm, rimmed (what do you expect of a military cartridge that has been in frontline use >100 years). Most of the post WWII use of the round was in belt feed machine guns (like the Goryunov and PK "series"), with I think use a heavier/longer bullet.

I think that when the Finns "standardized" the Model 1939 they also changed the bore diameter from the original "Russian" specs. I think that M39 Barrels are SAKO, but M24, M27, M28 are SIG (Swiss). I wish I had a "true" referance to quote, but they may have reduced the bore from .310 to .308.

Other Info:

The bolt assembly is made up of three parts:

1. bolt head
2. connecting sleeve (bar)
3. boly body

When the firing pin is screwed into the bolt,the rear of the firing pin should be flush with the the cocking piece. and that the marks on the rear of the firing pin are aligned with those on the cocking piece.

The Mosin-Nagant rifle has a "interrupter-ejector (or "distributor-ejector; or Ccartridge valve-ejector). No other rifle uses (or needs) this device.

Basically, when you are "working" this rifle there are a "more things going on" than with most other bolt action designs.

[wierdscience]

I would start by making a Cerrosafe chamber cast to verify that there's nothing in the chamber causing the hard closing. If it's ok, then think about lapping/polishing the bolt face very lightly, too much and you'll increase headspace.

That was my first thought,something in the chamber,but after looking at the spent rounds the copper wash is polishing off on the chamber side of the rim.That tells me it's seating in the chamber but good.

[wierdscience]

There are several different specs and types of 7.62x54mm, rimmed (what do you expect of a military cartridge that has been in frontline use >100 years). Most of the post WWII use of the round was in belt feed machine guns (like the Goryunov and PK "series"), with I think use a heavier/longer bullet.

I think that when the Finns "standardized" the Model 1939 they also changed the bore diameter from the original "Russian" specs. I think that M39 Barrels are SAKO, but M24, M27, M28 are SIG (Swiss). I wish I had a "true" referance to quote, but they may have reduced the bore from .310 to .308.

Other Info:

The bolt assembly is made up of three parts:

1. bolt head
2. connecting sleeve (bar)
3. boly body

When the firing pin is screwed into the bolt,the rear of the firing pin should be flush with the the cocking piece. and that the marks on the rear of the firing pin are aligned with those on the cocking piece.

The Mosin-Nagant rifle has a "interrupter-ejector (or "distributor-ejector; or Ccartridge valve-ejector). No other rifle uses (or needs) this device.

Basically, when you are "working" this rifle there are a "more things going on" than with most other bolt action designs.

Okay,ya I am going to check ammo.What I have now is S&B,I think I may order a small box of Wolf and some of that Chezk stuff and see if there is a difference.From what I have read,the Chezk in the spam can seems to be the best.Maybe it's sloppy enough to "interchange" in all the variants:D


I did check to see if the primers were pressed in pregnant and they checked at .002" recessed so no problem there.

The guy I got the thing from had two of them.I think I'll ask him if there was any chance bolts got swapped.

[38_Cal]

You may also want to turn a ring to accept the case up to the rim, and check the rim thickness. It's possible that your bolt is under minimum headspace distance for the ammo you've got, it's also possible that the ammo is over maximum for SAAMI/CIPS rim thickness. Nominal is .063", I believe. Don't know what the allowable tolerance is, though. You may want to call Dave Manson tomorrow at Manson Precision Reamers, 810-953-0732, to get the dimensions. Tell him (or Dara, his all-knowing office gal) Hi! from me.

[TECHSHOP]

:It has been years since I have looked at some dusty books on the self:

From an American reloading manual:

7.62x54R mm
rim thickness: .068"
length of "brass": 2.114"
Max OAL: 3.037"

From a Finnish reloading manual:
7.62x53R mm
rim thickness: .063
length of "brass": 2.106"
Max OAL: 3.031

The Finnish book offers both 7.88mm (.310") and 7.83mm (.308") data for this cartridge, stating that both are common in Finland.

Edited to add:

The M24 barrels are SIG, the M39 barrels are SACO, the others models could be from either. The last use that I know of the Finns were still using the original "Russian" receivers in their latest sniper rifles, but they don't look like your great grand pappy's Czarist rifle.

Also a bit of worthless trivia:

The Russians of the 1890's intented for a bayonet to be fixed on the rifle at all times, and actually "factored in" the change the long bayonet did to the point of impact down range.

[x39]

Also a bit of worthless trivia.
And a bit more... the Russian sights are not graduated in feet or meters, but in "Arshins", and Arshin being the regulation pace of a Russian soldier, or about 30".

[wierdscience]

And a bit more... the Russian sights are not graduated in feet or meters, but in "Arshins", and Arshin being the regulation pace of a Russian soldier, or about 30".

Thanks for that,the rear sights made no sense until now.

[wierdscience]

On further inspection there seems to be a healthy build up of copper in the barrel.What's the best chemical for the job?First thing that popped into mind was PC board etchant:)

There also looks to be a small wad of copper or crud just at the begining of the rifling.

[x39]

.What's the best chemical for the job?
I like Birchwood-Casey Foaming Bore Scrubber.

[wierdscience]

The bore cleaner along with adjusting the firing pin has done the job.Just a little more tweaking and it should be ready.