9mm Case Head Separation

[CQB45ACP]

I showed a picture of and mentioned this yesterday in the “What have you done” thread but wanted to start it’s own thread because it’s been eating at me.

Anyway, as I’m decapping & sizing cases, I found the pictured case when it wouldn’t drop in the gauge. I don’t recall feeling anything out of the ordinary while sizing. I certainly didn’t notice anything when I shot it on Friday. Seems like, but for the gauge, I wouldn’t have found it until I was priming for another reloading.

I have many questions (mostly second guessing myself) such as what did I miss BEFORE I loaded this case? I’ve looked at many past threads on case head separation with the overwhelming number being about rifle, not handgun.

I used the pictured pick inside this and other cases without any indications of incipient separation. (First use on “incipient“ in a sentence in my life.)

Thoughts and comments welcome.

 

[CQB45ACP]

Guess I should say—

This is a well used Winchester case—at least a dozen reloadings.

Most of those would’ve been with an undersized sizing die.

No expanding, no flaring, no crimping.

All moderate load of 4.5gr Sport Pistol & 115gr RN shot out of same 1911.

 

[Palladan44]

Is it possible this one piece came from elsewhere at one of the 12 times it was picked up from the floor?
9mm carbines fired from AR type guns will bulge the brass out like a mushroom in the head area, kind of like an Uzi. Kind of like a glock "smile" that goes all the way around. Just a guess.

Chain of custody for a dozen firings on 9mm brass, I'm sorry..... LMAO.
Dozen reloadings of 9mm brass sounds like they've had a good life....maybe time to move on.

 

[drband]

This is a well used Winchester case—at least a dozen reloadings.

I would hazard a guess that you just flat wore out that case. If the dozen or so loads using undersized dies exclusively, makes me wonder if the case wall “work-hardened” somehow, assuming that the chamber of the gun was generously sized.

Very interesting to see that in a 9mm case.

 

[CQB45ACP]

Is it possible this one piece came from elsewhere at one of the 12 times it was picked up from the floor?
9mm carbines fired from AR type guns will bulge the brass out like a mushroom in the head area, kind of like an Uzi. Kind of like a glock "smile" that goes all the way around. Just a guess.

Chain of custody for a dozen firings on 9mm brass, I'm sorry..... LMAO.
Dozen reloadings of 9mm brass sounds like they've had a good life....maybe time to move on.

Thanks

It’s possible but unlikely they’re someone else’s. Since may/June I only use Winchester and all with my red sharpie mark at a range where I’m often alone or at least no other shooters at that time. But again it’s possible.

“Time to move on” sounds so sad, reminds me of Nancy in college but that’s another story. But maybe it is time.

 

[CQB45ACP]

I would hazard a guess that you just flat wore out that case. If the dozen or so loads using undersized dies exclusively, makes me wonder if the case wall “work-hardened” somehow, assuming that the chamber of the gun was generously sized.

Very interesting to see that in a 9mm case.

Funny you say that. The case drops in barrel normally—tested it ten minutes ago—but not gauge.

 

[AJC1]

Over working a section of the case that is intended to be hard results in fracture. In and out is brass movement and undersized is a larger movement.

 

[CQB45ACP]

Over working a section of the case that is intended to be hard results in fracture. In and out is brass movement and undersized is a larger movement.

If so, I’ve just found what I was cautioned about on a thread I did a few months ago. I think it was when @Walkalong said he cared

I was looking for an actual downside to using an undersized die, not just theory. This may be it.

Thanks

 

[AJC1]

If so, I’ve just found what I was cautioned about on a thread I did a few months ago. I think it was when @Walkalong said he cared

I was looking for an actual downside to using an undersized die, not just theory. This may be it.

Thanks

I tend to give what that guy says some thought...

 

[MEHavey]

I used the pictured pick inside this and other cases without any indications of incipient separation.

I'm not seeing (and apparently you're not finding) incipient separation.
Perhaps, however, the oft-cited base-bulge of many such 9mm auto pistols?

Forget the case gauge.
Does it 'plunk' in the barrel ?

 

[CQB45ACP]

I'm not seeing (and apparently you're not finding) incipient separation.
Perhaps, however, the oft-cited base-bulge of many such 9mm auto pistols?

Forget the case gauge.
Does it 'plunk' in the barrel ?

Use both as necessary. Been at this a while.

Case for example fits barrel but not gauge in this instance

 

[Palladan44]

Thanks

It’s possible but unlikely they’re someone else’s. Since may/June I only use Winchester and all with my red sharpie mark at a range where I’m often alone or at least no other shooters at that time. But again it’s possible.

“Time to move on” sounds so sad, reminds me of Nancy in college but that’s another story. But maybe it is time.

Got it, red sharpie makes for no doubt it's yours.

I would think you'd get a split case before you'd get a CHS. It doesn't appear that your bending or shearing the brass in a way that would weaken it in that area, (like the glock smile, etc)

My old W. German SIG P228 has a gigantic chamber. It will literally chamber a spent casing fired from one of my glocks. I call it the AK-47 of handguns, because of that and the stamped steel slide, oh yeah and it shoots, every time... But I'd imagine loading for this gun over and over using the same brass I'd run into problems in short order.

 

[film495]

can someone explain what I'm looking at in that picture? what is the little line that appears to go all the way around? is that how far the sizing die goes on the case? and the bulge is lower than that ring? the ring I'm seeing makes me think the case is going to split there and I'd drop it in my bad brass tub, or into the sample of failed cases container for future reference, but not fully sure what I'm looking at. Is that from not setting the sizing die all the way down to the shell plate or is that just is what it is and time to get a new batch of brass? If that is from a batch, are you going to take that as a sign of impending failure of the batch and retire it?

 

[edwardware]

9mm Case Head Separation. . . I used the pictured pick inside this and other cases without any indications of incipient separation.

Based on your photo and description, it's not.

It appears to be a 9mm case, with an unusually visible end to the portion reached by the sizing die. Either the die was smaller, or the case head larger, than usual.

 

[GeoDudeFlorida]

I’ve just found what I was cautioned about on a thread I did a few months ago.

Yes.
Also, the case head is still attached to the case body so what you’re seeing is not an, “incipient case head separation,” but a circumferential crack in the case at the head. Those can be caused by an extractor if a long list of “if’s” is satisfied but more typically by work hardening of the case at the taper where the head begins to form.

It’s a trade-off: reduced case life vs. reliable feeding.
ETA: on more close inspection I can’t really tell if there’s a crack or thin spot that could result in a case head separation so it could be an incipient separation or it could be a full crack. Not sure from the pictures.

 

[peels]

I agree with @edwardware. I have seen this type of marks on brass on both pistol and rifle. It's not cause head separation. Just from brass sizing. I don't think it's even possible to stretch 9mm brass to get the body the separate unless the load is excessively hot.

 

[CQB45ACP]

Got it, red sharpie makes for no doubt it's yours.

I would think you'd get a split case before you'd get a CHS. It doesn't appear that your bending or shearing the brass in a way that would weaken it in that area, (like the glock smile, etc)

My old W. German SIG P228 has a gigantic chamber. It will literally chamber a spent casing fired from one of my glocks. I call it the AK-47 of handguns, because of that and the stamped steel slide, oh yeah and it shoots, every time... But I'd imagine loading for this gun over and over using the same brass I'd run into problems in short order.

In my range world, yes, red mark is ME. Range only has 15 bays and usually only three or so shooting when I’m there and we know one another.

 

[CQB45ACP]

can someone explain what I'm looking at in that picture? what is the little line that appears to go all the way around? is that how far the sizing die goes on the case? and the bulge is lower than that ring? the ring I'm seeing makes me think the case is going to split there and I'd drop it in my bad brass tub, or into the sample of failed cases container for future reference, but not fully sure what I'm looking at. Is that from not setting the sizing die all the way down to the shell plate or is that just is what it is and time to get a new batch of brass? If that is from a batch, are you going to take that as a sign of impending failure of the batch and retire it?

The line is the crack around maybe one third of case. It is right at the bottom of the wall at the base/webbing of case.

I didn’t see the line when loading that particular case I DONT THINK. But did I look closely enough? Maybe not.

I have now looked at the other cases ready to go and don’t see a line on them either.

Good questions. Got to figure out what I’m going to do.

 

[fxvr5]

That's produced by sizing an overexpanded case, and/or misalignment of the sizing die and the shell holder where the case is not perfectly aligned with the size die.

 

[CQB45ACP]

Yes.
Also, the case head is still attached to the case body so what you’re seeing is not an, “incipient case head separation,” but a circumferential crack in the case at the head. Those can be caused by an extractor if a long list of “if’s” is satisfied but more typically by work hardening of the case at the taper where the head begins to form.

It’s a trade-off: reduced case life vs. reliable feeding.
ETA: on more close inspection I can’t really tell if there’s a crack or thin spot that could result in a case head separation so it could be an incipient separation or it could be a full crack. Not sure from the pictures.

Thanks for that.

To me, It looks like a sharp crack formed just at the base about one third of circumference but honestly can’t tell if it’s about to go the rest of the way.

I’m considering just going back to regular sizing for a while.

 

[film495]

Do you have an pictures of some of the other ones that are ready to go? Some people on here can see things like they have xray vision, probably seen it all 100 times before, still amazes me.

 

[GeoDudeFlorida]

Thanks for that.

To me, It looks like a sharp crack formed just at the base about one third of circumference but honestly can’t tell if it’s about to go the rest of the way.

I’m considering just going back to regular sizing for a while.

I don’t think I would trust it again. It might be worth the time to do a water test: fill the case past the crack and apply pressure. If it leaks, it’s through; if it holds its just a visible artifact.

 

[CQB45ACP]

Do you have a pictures of some of the other ones that are ready to go? Some people on here can see things like they have xray vision, probably seen it all 100 times before, still amazes me.

I’ll get some later but hopefully before the champagne

 

[CQB45ACP]

I don’t think I would trust it again. It might be worth the time to do a water test: fill the case past the crack and apply pressure. If it leaks, it’s through; if it holds it’s just a visible artifact.

Oh no, I won’t use this case again if that’s what you meant. Crack is completely through. I meant just regular sizing die from here on out.

 

[Palladan44]

I showed a picture of and mentioned this yesterday in the “What have you done” thread but wanted to start it’s own thread because it’s been eating at me.

Anyway, as I’m decapping & sizing cases, I found the pictured case when it wouldn’t drop in the gauge. I don’t recall feeling anything out of the ordinary while sizing. I certainly didn’t notice anything when I shot it on Friday. Seems like, but for the gauge, I wouldn’t have found it until I was priming for another reloading.

I have many questions (mostly second guessing myself) such as what did I miss BEFORE I loaded this case? I’ve looked at many past threads on case head separation with the overwhelming number being about rifle, not handgun.

I used the pictured pick inside this and other cases without any indications of incipient separation. (First use on “incipient“ in a sentence in my life.)

Thoughts and comments welcome.

View attachment 1187042

Are you also positive these are all from the original same batch of once fired (or new) cases? I've came across a bunch of one-offs in my single batch brass over the years.

Even if not, they usually fail one at a time.
Ever notice cracked cases usually manifest themselves one (or 2)at a time?

Just toss it, and move on. I'd say you're just fine to continue loading your others.
You monitor your brass probably better than most, you've proven that. Carry on and don't let this make you flinch and start jerking your shots wondering if you've got an imminent CHS on deck!!! LOL.