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Discussion Starter #1
Hi All,

I sure could use some help here.

I don't know much about overpressure situations. My new-to-me M44 Mosin-Nagant was exhibiting a "sticky bolt" while shooting some Russian surplus ammunition from 1986.

It has no problem shooting heavy ball from Hungary made in 1951. The action is very slick using that stuff and I can reach over and operate the bolt handle with no problem (I'm a lefty). The ammunition is copper washed steel.

The Russian stuff is light ball. It has a laquered case mouth and primer, and the case is not laquered. It is copper washed steel as well.

When I first fired it I could hardly get the bolt open. I then came to the internet forums and found that the Mosin-Nagants have "sticky bolt syndrome." I followed the steps to correct this.

While it helped somewhat, the problem still existed.

I took a closer look at my spent cases. This is typical of what I found on the Russian stuff.


At first I thought these were a couple scratches, perhaps manufacturing defects.


I then noticed that the case is cracked, with light visible through the crack.

The rifle is OK. It's sturdy, if not purdy :)

Can someone tell me if this is a sure sign of overpressure? I don't know what else to look for; I've never seen an example of a flattened primer.

The bands which go around the cases look to be from some sort of annealing process. Looks like other heat treated metal I've seen.

Also, this ammo blows moisture of some sort back. Is this indicative of anything?

Overall, what exactly am I looking at gents? Over pressure, or is this typical of Russian stuff?

Personally, I think hard extraction + random case ruptures = overpressure.

The case code is "60" at 12:00 and "86" at 6:00 for those who may be wondering. I do not have a lot number.

Any help is appreciated.

Thanks,

Josh <><
 

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Howdy Mr. Josh,

If you can post a pic of the bottom of the fired brass (primer clearly shown), then we can probably say if you are showing primer flattening or not. Flattened primers are one indication of excessive pressure.

twoguns
 

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Hi there Josh.

It seems typical to my experience. A throat-erosion gauge might shed some light on the portion of the case that is showing cracks or ruptures, but I've had a few neck cracks and splits with 1986 USSR-mfr. ammo.

The worst/most alarming ammo mishap I've had with a Mosin was a very long time ago. It involved using Yugo-mfr. brass cased 7.62x54r ammo in a Finnish M-91. I got two pierced primers. In retrospect it might have been the firing-pin reassembly issues, or it might have been the ammo.

You are right about the annealing/heat treatment on the cases. That was done so it could work in PK machine guns. The moisture bouncing back during recoil might just be lube from the bolt?

Sticky bolt: In my admittedly limited experience this surfaces when the rifle gets hot. I was shooting prone with the M91 with the sun beating down and firing rapidly (well, for a Mosin that is) when the bolt seized about half-way up and would not budge. From the sounds of things you've done a thorough job of cleaning the chamber. I'm not sure if it is the ammo or the bolt head tolerances, but from what you've said the chamber seems OK, yes? You might have to find a gauge for throat erosion or to check the dimensions of the chamber vs. the cartridge. It might be telling that the older ammo seems to "fit" the chamber, while the more recent ammo does not. Machine-gun ammo? SVD vs. Mosin Nagant?

Shooting a 7.5mm Swiss M1911 Schmidt-Rubin Langgewehr years ago I've also had bulged cases and a cracked case too, fwiw, so such problems are not the exclusive preserve of Mosin Nagants.
 

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Discussion Starter #4
Thanks guys,

Here are some pics that may help:

So far as I know zinc is not involved. The cases are advertised as copper washed steel with red laquer sealant.

I do not have the pic of the SPAM can it came out of... but I do have some other pics for ya'll:


Head-on primer view, comparison fired and unfired.


I'm attempting to show the primer depth here. I don't know if this is normal.


Case length comparisons.

Is it just me or does the OAL of the Russian stuff look to be shorter than the Hungarian heavy ball? Photos don't do it justice; the unfired Russian case is definitely shorter in length to the shoulder and to the mouth.


Circled is the bulge which will not let me chamber one of these spent shells.

The bulge is present on every fired case I've examined, and is the reason it's not extracting properly. The laquer has very little to do with it and there can't be any cosmoline left in the chamber anyway, after the cleaning I gave it over the course of two days. Remember, this involved a 20 gauge brush and drill as was recommended.

I was told that the burn rate can change over the years. The ammo is moved around and while it may start out as granules or flakes, the continuous movement gradually makes it finer. Does this make sense?

Any comments? It's only doing this with the Russian light ball.

Thanks,

Josh <><
 

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I'll be darned.
It sure looks like the USSR case is a bit shorter in the case shoulder and mouth like you described. And the fired primer is really bulged out from the pocket, that is for sure. Is there a way to measure the case dimensions a bit more? 7.62x54r.net has that 1986 dated ammo rated favorably in most rifles they tried. I've still got an opened spam can of that 1986 stuff with the paper packets of 20rds. about half full. I'll have to check it against the info you've got here to see if it is the same. I have experienced some of the same case shoulder issues with my M44, but I don't know if I've seen a bulge after firing like that.

more later.
 

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Discussion Starter #6
Dave,

My micrometer broke a couple weeks ago and I've not replaced it yet. The closest I can come is a ruler.

I did just fire some yellow tip and after cleaning the chamber and polishing some rough spots on the bolt trying to clear up this other issue, the thing is slick, feeling almost like a stock Rem 700 (I know, blasphemy!)

Thanks,

Josh <><
 

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Hello,

I'd agree with Dave that you probably have machine gun ammo that was loaded for higher operating pressures that has been delinked, boxed and exported to the US.

Chris
 

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Hi again,

Got home and rummaged through the ammo I've got.
Sure enough, I've been shooting the same 7.62x54R light ball marked factory "60" and "86" as you have, with the laquer seal at the bullet crimp and on the primer. I thought I had more variety of rounds, but the only other I've still got that I haven't shot yet is a JSP round with the same kind of case (copper-washed steel) that reads "LVE" and 7.62x54R on the case head, which I'm sure is a commercial round, probably Russian provenance. The case rim seems thicker on the "86" stuff, and just eyeballing it, it would seem the case is about 1mm shorter. The case shoulder seems about the same though. Heck, its probably the same factory!
I've been meaning to put my M1891/59 through its paces some more, so when I get back from the range I'll let you know what the cases are looking like in my experience. Thanks for bringing this up, it is a mystery. I'll have to get some S&B Czech and Wolf/Brown Bear/Prvi Partizan/ etc. commercial ammo to compare. It definitely looks like that 86 round is a culprit for "sticky bolt" in your particular rifle.
That's quite a photo down the bore you have there. Doesn't seem too bad, "frost" as they say, but the rifling looks OK. From your description of cleaning it and so on (Rem. 700??! Heresy indeed!) it sounds like it has been restored to shooting condition and then some. You might find you'll shoot out and clean out sixty years of gunk and have a mighty serviceable piece there.
 
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