The Russian Mosin Nagant Forum

Took the M39 out this past weekend and had a couple cases split and got a face full of wonderful smelling gases. I'm guessing it is an ammo issue, but I've had this batch of ammo around for a number of years and never noticed this happening before. Two cases split in the same spot. Most of the split cases I've seen pictures of have been up in the neck of the case. What do you think is going on here? The gun passed a field head space gauge.

Yea, case failure, being that they are in identical spots on more than one case I suspect a weak spot in the brass. Take the rest of that lot and put it aside for use as reloading components.

If it keeps on splitting cases, see if an unfired round will move at all when its in the chamber. It's hitting the primer slightly off center.

Three questions:

Do you have problems with any other ammo in this rifle?

Do you have problems with this ammo in any other rifle?

Did the rifle pass substantially on the field gauge (one of mine I hope) or did it just barely pass?

You can also change out the bolt with another that will pass headspace on a go gauge and see if you still get split cases. From where they are splitting I would guess it is weak cases. I seem to remember some bad cases around a few years ago.

websterz wrote:Three questions:

Do you have problems with any other ammo in this rifle?

Do you have problems with this ammo in any other rifle?

Did the rifle pass substantially on the field gauge (one of mine I hope) or did it just barely pass?

I do not have problems with the other type of surplus ammo I've tried in the rifle. But I have not had issues with the ammo which had case splits occur in other rifles.

Yes, I only use your gauges for my rimmed rifles. It passes the field with the bolt handle moving about half way between vertical and horizontal. So I would consider that passing quite well.

steelbuttplate wrote:If it keeps on splitting cases, see if an unfired round will move at all when its in the chamber. It's hitting the primer slightly off center.

I put a round from the same batch into the chamber and it fits tightly.

Definitely sounds like it's just bad brass. If you don't have hundreds and hundreds of rounds of the stuff then I would disassemble it for components. If you do have a ton of the stuff then I don't know what to recommend.

Thank you all! That's what I was thinking as well. I've probably got a couple hundred rounds of it still. I'll just shoot it out of the other guns that for whatever reason don't seem to have an issue.

I just remembered , I got a can of '46 Russian ammo because it was on clips, opened it and saved the clips. I took some of the ammo to the range one day and it did this same split. About every other round. Does older brass get weak just from age?

steelbuttplate wrote:I just remembered , I got a can of '46 Russian ammo because it was on clips, opened it and saved the clips. I took some of the ammo to the range one day and it did this same split. About every other round. Does older brass get weak just from age?

This stuff was not always stored under ideal conditions, and as such it will degrade over time.

websterz wrote:

steelbuttplate wrote:I just remembered , I got a can of '46 Russian ammo because it was on clips, opened it and saved the clips. I took some of the ammo to the range one day and it did this same split. About every other round. Does older brass get weak just from age?

This stuff was not always stored under ideal conditions, and as such it will degrade over time.

This came out of a sealed 330 rd can, packed in cardboard boxes. It wasn't shiny, but it looked good didn't have green shit or other corrosion.

It happens. I shot hundreds of rounds of Czech 80's surplus and one round did exactly as yours. I look over each round more closely now. Startles the hell out of you, that's for sure.