Case head separation?

jimbires

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Mar 16, 2008
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clearfield county , Pa
Dang! 308 Win?
I've had 2 case head separations over thousands of rounds across all my calibers - my necks or primer flash holes usually give out first!



this brass was just worn out. it's my 338 Lapua , using Lapua brass . I think this was reloading cycle # 15 on that batch of brass . proof that brass can have a long life , even using + pressure loads . 300gr bergers at 2939FPS .
 

nicholasjohn

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Feb 12, 2019
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Vancouver, WA
I don’t think it would be case head separation on first firing.

So you all are saying it’s just normal to expand to chamber? I tried rubbing a paper clip, and don’t think I felt anything but powder residue, but I’ll research the paper clip method some more.

Thanks,
Steve

Look over some of your other once-fired cases, and you'll see pretty much the same thing - just maybe not as pronounced. This one looks pretty normal to me. Also, if you measure the diameter of a case head immediately above the extractor groove, it may be a tiny bit smaller than the brass you have been shooting, so there may have been a little more expansion of the case walls to fill your chamber than what you're used to seeing. This would make the pressure ring more noticeable to the naked eye.

To make this measurement, you're going to need to do it on an un-fired case, because both the rim and the pressure ring are bigger around than the case head once the case has been fired. Then compare that to other brass you've used, and you may find that it's a little smaller at the head. ( On a fired case, you would need a blade mic to get down between them to make the same measurement, since the a regular micrometer has posts that will be measuring at the larger diameter.) You won't really need to get that measurement on a fired case to learn what you want to know. Also, the composition of the brass may be a slightly different alloy than other brands of cartridge brass, and this may make the pressure ring more obvious to your eye.
 

mechengr

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Jan 7, 2014
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146
I have some 280 Rem brass by Hornady that looks exactly like that, I thought it was case head separation at first too but couldn't feel anything using a hooked wire inside the case. Just been shooting them and no issues thus far, and no changes to the cases' condition since the first firing with 3 firings on some of them now.

I now think it's just my chamber and that batch of brass must have been on opposite ends of SAAMI tolerance . That region is right where the case web thins to meet the case wall so on first firing the wall is going to expand to fill the chamber but the thicker web section won't expand as much which give the slight bump on the outside of the case.

So long as you don't bump headspace too much when resizing from here on out you should be good to go.
 

BallisticsGuy

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May 8, 2016
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Heck
I separate quite a few .223 cases. Usually the failure point is around halfway up the case. I don't know what others get but I don't see it at the base with that particular chambering.
 

BoomFlop

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Oct 16, 2012
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Wisconsin
Dosh

They were fired out of a bolt action Sir.

I did the “paper clip” check and I don’t feel anything.

Steve
 

Quarter Round

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Sep 28, 2005
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Location
WV
I don’t think it would be case head separation on first firing.

So you all are saying it’s just normal to expand to chamber? I tried rubbing a paper clip, and don’t think I felt anything but powder residue, but I’ll research the paper clip method some more.

Thanks,
Steve

Imagine or bend a paper clip with a small hook on the end. The clip must be long enough to reach the inside base. Insert and drag up the inside with the modified paper clip. You may need to sharpen the hook end for a better feel.
__________________
| _______)

"Clip", not to be confused with a gun clip. :>))
 

tnek13

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Feb 26, 2012
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160
Location
NW Indiana
The firing pin drives the case forward against the chamber shoulder, firing the case causes the brass to fill the area available, the portion of the case beyond the chamber walls housed in the bolt head can stretch, which is normal. If only a few of your pieces are showing what you have in the photo this should not be a problem, however, if you are concerned beyond what everyone has spoken, call Starline, they are good people and stand behind their product.
 

BoomFlop

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Oct 16, 2012
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Location
Wisconsin
I confirmed with Hunter at Starline today. He said what was mentioned, that the case head can’t expand and that if it was case head separation it would be further up the case.

Thanks all
Steve
 
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