Rupture of 8mm casing

[Willi Z.]

I opened a 15-round box of '44 dated S.m.E. ammo and one of them looked like this. I guess this stuff is getting near the end of its life. I certainly have seen lacquered steel casings rupture, but this is the first brass casing I have seen. I guess the steel primer of the late S.m.E. round, as well as the iron core of the bullet, contributed to this.

[Wilhelm]

That is just strange. I have never seen an un-fired case rupture. I have had the lacquered steel cases rupture when fired but this is a first. Looks like a Wurst when cooked over a fire.
Wilhelm

[phild]

At some point or even over a period of time in that cartridge's life it was exposed to a very corrosive substance. The corrosion of the iron in the bullet core appears too me to have expanded to an extent that it caused the rupture. It's more difficult to account for the severe patches of corrosion on the brass case, but I would guess that it was caused by leeching from whatever caused the corrosion inside to the iron.

[Wilhelm]

Did the box look like it had any water damage?
Wilhelm

[DaveR]

please correct me if i'm mistaken, but I believe the core of these projectiles are lead not iron, with a copper or steel jacket.

[leondes]

Hi Dave,

S.m.E. means iron core.

Hi Willi,

I have sorted through many thousands of rounds of Third Reich 8mm ammo. What I have seen mostly is that the steel cases corrode from the inside. So, I assume the powder was corrosive. A friend of mine cut a case lengthwise so you could see how the corrosion was mostly on the inside and would eventually break through to the outside but it would usually just look like a pin hole. I never came across a round like the one you have.

Regards, Leon

[Willi Z.]

Leon, I agree that I have seen quite a few steel casings corrode. But, I never knew the powder was corrosive. I thought the primers were. Not sure what causes the breakdown of the steel casing; I guess we need a chemist to weigh in.

Here is the S.m.E. box and the rounds. Note another round is in bad shape as well. But, the steel primer doesn't seem to be corroded. The box doesn't seem to indicate bad storage.

[Willi Z.]

The other round.

[phild]

I know that primers can "leak". By the looks of the primer on this one, that happened. Maybe if the round was nose down on the box for a very long time the corrosive primer compound worked through the powder (or just reacted with it and "made" it also corrosive) and corroded the iron core below in the bullet.

That is my best and somewhat educated guess on this one.

It seems extreme that this much primer compound would/could get through those two tiny Berdan holes in the base......but it was either that or the powder was contaminated with something when the case was loaded......a worker's lunch salt?

I do not think that most (if any) smokless powder of the nitro cellulose type is corrosive in itself....but I do know that it can and will in time breakdown, corrode and basically rot when long exposed to moist air, oxygen and to some degree light......those things do not seem to be the problem here with your cartridge given the condition of the box and the other rounds.

[Peter C]

One of the members on another forum is an avid ammo collector and mg shooter. He has indicated that in 1943 the process for manufacturing powder was changed in that certain steps were eliminated to speed up the process. Due to these shortcuts the powder is or becomes acidic which in turn corrodes the cartridge from the inside out. This is very common in late war steel cased ammo. I tried to find the topic on the other forum so that I could link it here but to no avail.

BTW the primers used in Willi's round are non corrosive.

[phild]

You are right about these primers being non-corrosive, I missed that fact when I looked at the packaging the first time. They are, however, the type made with zinc coated steel primer cups as opposed to zinc coated brass primer cups, so are more prone (IMO) to corrosion.

I could believe that the powder was more acidic due to some kind of chemical changes in the production, we are therefore back to a reaction between the propellant and the iron core.

[Frank De Smedt]

Willi,

This type of tear is mainly caused due improper heat treatment of the casing after forming.
Modern ammo has a bluish color on the neck due to annealing.
This treatment was often forgotten.


FRANK

[Gary Cain]

This occurs over time with heating and cooling cycles which causes the fulminated mercury to sweat. This will attack the inner wall of the case and eventually it is pierced and moisture gets in. I have seen other cartridges like this (usually stored in garages and barns etc.) but I must admit yours is probably the worst I've seen.

[Willi Z.]

Gary, that makes perfect sense. You can see how the powder near the bullet has been impacted the most. Not sure about the powder near the primer.

Yes, the worst I have seen as well.

[lmg34]

Hi,
here another ruptured S.m.E. cartridge from Polte of 1944, but different batch. The mouth case is cracked at several points and the primer is totally rusted. From 15, also only one at this condition.

Antoni