The Russian Mosin Nagant Forum

I just purchased my first Mosin (91/30), disassembled and cleaned it according to the best resources I found on the web, reassembled it, and took it for a test run. It seemed to fire just fine, pretty accurate at 25 yards, and seemed to perform normally. Ammos used is the standard surplus Russian stuff available everywhere in 440 round tins and 880 round cases. As I always do, I kept some of the casings, just my thing to have a few casings from my first use of a new weapon. Upon examining them at home later, I found something that surprised me: some of the casings had cracked at the neck, a couple of them quite seriously. I'd appreciate your feedback on these; is it an ammo problem? is it a rifle problem? did I not clean or assemble it right? and most importantly; is it dangerous?
Thank you for your input, photos below:

A few split necks are normal with the ammo that is in the last batch of older stuff. Examine it before shooting and take out the really bad ones if the bullet is loose. It seems that the older 40s on the strippers is splitting, but should not be a big problem. There are a few threads on here if you search that talk about this subject.

BTW, it's a 1943 Izhevsk...in case that may be important.

What year is the ammo?

From these markings, I assume 1971?

That's 1971 Bulgarian. It might be the ammo but it may also be the rifle. You may have throat errosion in the chamber. I have a Polish M44 that splits cases just like that and the same ammo, 1985 Russian Lagansk Plant 60 ammo shoots in other rifles with no splits. Have you checked the rifles headspace? This might be caused by excessive headspace too. If not get some guages from Okie Headspace guages and check it. http://www.okiegauges.com/sales.html You'll need the field gauge at a minimum but it's nice to have the no-go and field. I bought the whole set but that was before Todd offered the no-go and field as a set. The Go gauge is not something most people will ever need. These are especially good to have if you plan on collecting more of these rifles as they work on all Mosin Nagants. Otherwise have the rifle inspected by a gunsmith.

Other things you can try if you have access to other Mosin Nagants is to fire the ammo in different rifles to see what happens or get some different ammo and fire it in that rifle but I'd still check headspace at a minimum just as a safety precaution.

Well noted; thank you.
I ordered the no-go+field set...better safe than sorry, I say!

Spacecase wrote:Well noted; thank you.
I ordered the no-go+field set...better safe than sorry, I say!

Keep in mind that even if the rifle passes headspace tests it might still have throat errosion and split cases. That Polish M44 I have passes the no-go and field tests but splits cases. The good thing about headspace testing is you eliminate at least one possiblility. Trying the ammo in different rifles as well as trying different ammo in this rifle are also steps to eliminate possibilities. If you don't have other rifles to do this with, well hang around here a while and you will.

Would throat erosion be caused by use? (abuse?)
If that turns out to be the case, is it dangerous to shoot it?

Spacecase wrote:Would throat erosion be caused by use? (abuse?)
If that turns out to be the case, is it dangerous to shoot it?

I'm no expert or gunsmith so keep this in mind. Throat erosion comes from repeated firing of the rifle and/or the use of corrosive primed ammo and not cleaning it ether soon enough after shooting or at all in some cases. Remember these rifles were used in battle and they didn't always have time to clean them as often as they should have. It's entirely possible it's the ammo but I haven't seen a lot of complaints of 70s Bulgarian specifically splitting cases. Reguardless checking headspacing is always a good idea and yes it could be dangerous depending on why the cases are splitting. One thing to think about too is was there any gunoil in the chamber? Most of us give them a coating of oil after shooting to store them and that oil should be cleared from the chamber and bore before shooting because even small amounts of oil can cause higher chamber pressures which can also cause case splits. If it passes a headspace check and the chamber looks intact I'd try different ammo to see if it splits cases still. If you don't feel comfortable making judgements about the state and condition of the chamber and rifles overall safety maybe a gunsmith should look at it. Always err on the side of caution.

Ive put about 300 rounds of Bulgarian through mine so far and haven't had any problems, seems like really good, clean ammo i'm a little worried to try anything else as this stuff seems really reliable.

jayrocka1200 wrote:Ive put about 300 rounds of Bulgarian through mine so far and haven't had any problems, seems like really good, clean ammo i'm a little worried to try anything else as this stuff seems really reliable.

I wouldn't be worried about any other ammo. There's a few cases of splits and a few duds but for the most part all of the surplus being sold right now is good ammo.

WeldonHunter wrote:

Spacecase wrote:Would throat erosion be caused by use? (abuse?)
If that turns out to be the case, is it dangerous to shoot it?

I'm no expert or gunsmith so keep this in mind. Throat erosion comes from repeated firing of the rifle and/or the use of corrosive primed ammo and not cleaning it ether soon enough after shooting or at all in some cases. Remember these rifles were used in battle and they didn't always have time to clean them as often as they should have. It's entirely possible it's the ammo but I haven't seen a lot of complaints of 70s Bulgarian specifically splitting cases. Reguardless checking headspacing is always a good idea and yes it could be dangerous depending on why the cases are splitting. One thing to think about too is was there any gunoil in the chamber? Most of us give them a coating of oil after shooting to store them and that oil should be cleared from the chamber and bore before shooting because even small amounts of oil can cause higher chamber pressures which can also cause case splits. If it passes a headspace check and the chamber looks intact I'd try different ammo to see if it splits cases still. If you don't feel comfortable making judgements about the state and condition of the chamber and rifles overall safety maybe a gunsmith should look at it. Always err on the side of caution.

Thanks for the advice; I will have my GS take a look at it as well.

I will just go ahead and add to Mikes advice by telling you to take a good light and some magnified reading glasses and look good at the chamber for dried cosmo and maybe pieces of brass.

It is the ammo. I have come to expect some split necks with almost any steel cased surplus ammo. Wear your shooting glasses and have a good time.

desdem12 wrote:I will just go ahead and add to Mikes advice by telling you to take a good light and some magnified reading glasses and look good at the chamber for dried cosmo and maybe pieces of brass.

Thanks. I actually spent over one hour cleaning the barrel of cosmoline, etc. before I was satisfied; I've never seen so many rounds of pads come out dirty from a barrel before. It certainly had a lot of crud, even thought I ran boiling water through it several times before that. I may just do it all again, although it cleaned fairly normally after my first test shoot. But a good look inside should be revealing; will have to figure out how to do that.

First off the early groups of heavy ball Bulgarian were where the initial problem with the Bulgarian was if that is Bulgarian light you will have occaisional neck splits like you are showing us. Now I will ask everyone if that does not look copper washed steel cased ammo? If it is that I have no Bulgarian that is not brass cased so maybe it is not Bulgarian?

Neck splits can be caused by the chamber reamer being pulled out while it is still spinning and making a mark in the neck of the chamber. If that is the case it can cause neck splits or least leave marks on just about every cartridge you put through the rifle. Hardened cosmoline if not cleaned completely from the chamber in the initial cleaning can harden in place and be very hard to remove at a later time requiring some heavy duty solvent or way too much spinning brush and solvent action to completely remove it. I am going to just guess you have a head space problem there too, by looking at those spent shells. I am going to keep you guessing why I say that till you get the guages and check that rifle. I am getting sneaky in my old age! Sorry! I will tell you why after you check the rifle if the head space is wrong. If it is all right the old man is really slipping I guess! Good Luck and be sure to always check ammo you intend to shoot before you do. Look for splits starting form, swelled primers, loose bullet fits, excessive sealer around the bullet and around the shell case, obviously thick rims versus others, and any other obvious problems as it saves time at the range and a possible injury to you or someone else near you at the range. Bill

Im pretty sure that's Bulgarian as the metal case lettering looks identical to what I recently bought

WeldonHunter wrote: …… One thing to think about too is was there any gunoil in the chamber? Most of us give them a coating of oil after shooting to store them and that oil should be cleared from the chamber and bore before shooting because even small amounts of oil can cause higher chamber pressures which can also cause case splits…..

I agree that oil should be wiped out but I do not agree that the oil would cause higher chamber pressure.

What oil does is lessen the friction forces between the cartridge case and chamber walls which will result in an increase of the force on the bolt face.

The pressure inside the cartridge case would be the same with or without the oil. The neck splits are caused by hoop stress in the cartridge case which is calculated by pressure * radius/2*(thickness of case). Since the pressure does not change, the hoop stress does not change. Thus oil would not cause the splits.

Hombre wrote:

WeldonHunter wrote: …… One thing to think about too is was there any gunoil in the chamber? Most of us give them a coating of oil after shooting to store them and that oil should be cleared from the chamber and bore before shooting because even small amounts of oil can cause higher chamber pressures which can also cause case splits…..

I agree that oil should be wiped out but I do not agree that the oil would cause higher chamber pressure.

What oil does is lessen the friction forces between the cartridge case and chamber walls which will result in an increase of the force on the bolt face.

The pressure inside the cartridge case would be the same with or without the oil. The neck splits are caused by hoop stress in the cartridge case which is calculated by pressure * radius/2*(thickness of case). Since the pressure does not change, the hoop stress does not change. Thus oil would not cause the splits.

I just read a post the other day that was part of a military article that addressed the fact that soldiers were oiling their ammo for a bunch of various reasons like trying to make it feed better. Post #37 http://m14forum.com/ammunition/108956-p ... ses-3.html

I know as an Auto tech when I check an engines compression I do a dry check and a wet check. The rings seal the combustion chamber but if I get a reading that's below specs. I squirt oil in the cylinder to see if it's worn rings or something else like a burned valve. If the rings are worn the oil will seal the combustion chamber raising the compression readings telling me it's worn rings and not a burned valve. Wouldn't the same thing happen to a cartridge in a chamber?