split case

[beag_nut]

Nothing important here, just an interesting case failure and a question.

The pic shows a nickle-plated .357 mag case, which had been reloaded 15-20 times, and which failed inside my SP's cylinder. A relatively mild ".38 spl. +P" load, which went off normally, and was noticed only during extraction, which was sticky. Interesting that the split did not extend to the very rim edge, but there is a tiny split at the rim a short distance away. All in all, just one less case left for reloading. Now the question: this was a W-W Super .357 mag case, plated. I seem to find three times as many plated cases to develop rim splits, compared to plain unplated brass. Any chemists/metallurgists out there who could explain why?

 

[ReloaderFred]

That's a pretty common split in .38/.357 cases. They wear out, just like elbows and knees do in people.

As to why nickel plated cases tend to split earlier than unplated cases, I believe it has to do with the plating process itself, which makes the brass more brittle. I separate my .38 brass, and only fire unplated brass in our Marlin rifles, and confine the nickel plated brass to the revolvers. A split case in a revolver is no big deal, but a split case in a rifle won't extract readily, so it locks up the rifle, which can be bothersome during a match.

Hope this helps.

Fred

 

[FROGO207]

I also have noticed that the plated brass will split sooner as well. Could be the plating process, could be it being worked harder because it is a regular case that has a thin layer of plating over the brass and therefore is squeezed down more when resized to make the same outside diameter as the regular brass ones. No matter, it happens with all plated brass as far as I can tell. That said I have some plated casings that have been shot so many times the stamp on the head is flat and the indent is the only place the plating is still on the cartridge. So some of them will survive OK. Seldom do I see splits any lower on the brass than what you show in the picture. Some will have many small fractures around the lip and I figure that is from the roll crimp working that area more. YMMV

 

[Ole Joe Clark]

If my memory serves me right, it's called hydrogen embrittlement. Something to do with not stress relieving after plating. Some of my brass is really old and it will fail. I don't worry about it, just chunk into the scrap brass can and move on.

Have a blessed day,

Leon

 

[Walkalong]

As noted, it's a fairly typical failure for revolver brass, and yes, nickle plated does it sooner than plain brass, but I have no idea why.

.32 Mag

.357 Mag. (Yep, a sideways split)

.45 Colt

 

[Jesse Heywood]

Hydrogen embrittlement due to the plating process. Due to the stresses, it usually shows at the case mouth. A microscopic analysis will usually show the crack is longer.
In one of the few times I will link to wiki, this article does a far better job than I can explaining the process.
https://en.wikipedia.org/wiki/Hydrogen_embrittlement
I learned a lot on the subject designing fasteners at Boeing. And I have forgotten much, too.

 

[FROGO207]

Good to know Jesse. I learned something today! This is what I like about this hobby, it keeps you interested in it.

 

[Fine Figure of a Man]

Us simple folks call it work hardening.

 

[243winxb]

Us simple folks call it work hardening.

And the nickel starts out harder than plain brass.

Old tired nickel will not spring back after firing, like plain brass, using the same load data in 357 mag. A micrometer tells the story.

 

[beag_nut]

Thanks to you all for your responses. Guess I may pass up nickel-plated range brass in the future.

 

[Walkalong]

No need to pass it up, I pick up all I can find, you will still get good life out of it.

 

[Fine Figure of a Man]

No need to pass it up, I pick up all I can find, you will still get good life out of it.

I wouldn't pass on any free nickle cases but the only ones I buy are 357's to make it easy to separate from 38's.

 

[DLrocket89]

Hydrogen embrittlement due to the plating process. Due to the stresses, it usually shows at the case mouth. A microscopic analysis will usually show the crack is longer.
In one of the few times I will link to wiki, this article does a far better job than I can explaining the process.
https://en.wikipedia.org/wiki/Hydrogen_embrittlement
I learned a lot on the subject designing fasteners at Boeing. And I have forgotten much, too.

Hydrogen embrittlement doesn't generally affect copper-based alloys though (I say this as a metallurgist myself, also the wikipedia article says that). I worked for an aerospace company that provided parts to Boeing and it was always high strength fasteners that caused problems...the stronger the steel, the worse the problem.

Work hardening would be my thought.