A subtle sign of risk of case head separation

[Cassidy]

I had a case head separation occur several months ago even though I routinely look for signs of excessive pressure on each case during each reloading. The cases in question had been reloaded 5-6 times. After the case head separation occurred in the one case, I looked much closer at the remaining fired cases and noticed a very slight subtle change at the location where the case head separation had occurred on the case that separated. Please see the pic below; the arrow shows a slight line on the remaining cases (this is where the separate occurred in the case that separated), indicating to me it was time to discard these remaining fired cases and load new ones. Both the old and new cases are shown in the pic so you can compare and see the slight change in the fired cases; the slight line shown goes only partly around the barrel of the case. I have to hand-rotate each fired case to see the slight line (arrow) under a lamp. I thought this info may be helpful to you.



Forum Boss: Guys, Read this article:

Incipient Case-Head Separation — How to Detect the Problem « Daily Bulletin

We are re-publishing this article at the request of Forum members who found the information very valuable. If you haven’t read this Safety Tip before, take a moment to learn how you can inspect your fired brass to determine if there may be a potential for case separation. A case separation can...

bulletin.accurateshooter.com

No you do NOT have to cut away the case, but this shows how a paper clip can detect a fault. Repeat, the case is cut ONLY for demo purposes.

 

[Cassidy]

I'd like to make the pic larger and clearer so you can see it clearer but so far have been unable to do so.

 

[nmkid]

Use the paper clip method to check the inside of the case.

 

[BoydAllen]

What you see there is called incipient separation, and is generally caused by repeatedly bumping shoulders back too far, not pressure.

 

[Big Mc]

I had a case head separation occur several months ago even though I routinely look for signs of excessive pressure on each case during each reloading. The cases in question had been reloaded 5-6 times. After the case head separation occurred in the one case, I looked much closer at the remaining fired cases and noticed a very slight subtle change at the location where the case head separation had occurred on the case that separated. Please see the pic below; the arrow shows a slight line on the remaining cases (this is where the separate occurred in the case that separated), indicating to me it was time to discard these remaining fired cases and load new ones. Both the old and new cases are shown in the pic so you can compare and see the slight change in the fired cases; the slight line shown goes only partly around the barrel of the case. I have to hand-rotate each fired case to see the slight line (arrow) under a lamp. I thought this info may be helpful to you.

Boyd is spot on . Tommy Mc

 

[ImBIllT]

Two pics show a rub that occurs from rubbing in an ammo box, and two show cases for which case separation is imminent. Notice that the rings from the ammo box are not faint, and are perfectly circular. The rings from case head separation are faint, and irregular.

The paper clip method works well on cases that where visual signs are difficult to see.

I had a batch of Lapua .308 cases that got over 40 reloads before they began to die of incipient case head separation. (Incipient just means starting to appear) The head has started to separate, but there’s no leak yet. Throw it away before a bigger problem arises.

 

[Cassidy]

I just carefully tried the paperclip method on those cases - tested 10-12 cases - all with the slight lines around the same area of the cases as where the separation occurred in the separated case. In each case (no pun intended) I could not detect any inside circumferential groove with the paperclip - the inside of each case at the separation area felt absolutely smooth with repeated tries. It could possibly be that such visually slight lines around the outside of the barrel of the cases toward the base could be a more sensitive test than the paperclip method. All comments are welcome.

 

[Paul Hilgedick]

If you have a bore scope take a look. You may need to clean the cases to see where the separation starts.

 

[ImBIllT]

What I’ve felt with a paper clip was very very subtle. The paper clip doesn’t snag on it. After feeling cases that were fine and cases that were fine and cases that were about to separate, the difference was subtle, but it was there and repeatable.

 

[Cassidy]

I tried my borescope, all 3 lens fixtures. The lateral fixture (with a mirror which looks sideways to see the inside sides of the cases) was too long; it hit the primer hole before I could see the inside side areas where the exterior slight lines were located toward the base. The other forward-looking lens fixtures (2 of them) showed the inside of the case toward the base (I could clearly see the primer hole; primer removed) though the sides of the inside of the cases I looked at (4-5) toward the base were not so clear but showed an expected amount of debris on the walls. I did not see any circumferential grooves though the images of the inside of the case walls were not crystal clear.

 

[358WCF]

I just carefully tried the paperclip method on those cases - tested 10-12 cases - all with the slight lines around the same area of the cases as where the separation occurred in the separated case. In each case (no pun intended) I could not detect any inside circumferential groove with the paperclip - the inside of each case at the separation area felt absolutely smooth with repeated tries. It could possibly be that such visually slight lines around the outside of the barrel of the cases toward the base could be a more sensitive test than the paperclip method. All comments are welcome.

Not sure of your procedure, but I sharpened my paper clip to a point with a bench grinder before bending the tip @90* & have no problem at all feeling even the slightest irregularity. Been using it this way for years & it still works just fine.

 

[M-61]

caused by repeatedly bumping shoulders back too far, not pressure.

I never understood why this would/has become a step in many peoples reloading procedure. I realize this in semi-autos and hunting rifles. (although with hunting rifles one can always take the cartridges they loaded and try them in their basement to see if they feed, cycle etc.) If the bolt chambers the cartridge properly what is bumping the shoulder do other than working the brass unnecessarily?
All I shoot is benchrest so that's what I am referring to. Bolt doesn't close normally it may be time to bump the shoulder.
Additionally the cartridges that I load the most are probably the easiest on the brass.(222,30BR,6BR)
No clue how many times I have reloaded my 222 brass but it's way up there. Never had to bump a shoulder.
I guess everyone has their own thoughts and these are certainly mine.
Am I a world champion shooter? Not a chance. But I do shoot the above mentioned in the 1's and 2's. (I wish that was all the time but it isn't)

 

[gambleone]

The line seems to be darn close to the case head. Could it be your sizing die which is stopping there?

 

[divingin]

I just carefully tried the paperclip method on those cases - tested 10-12 cases - all with the slight lines around the same area of the cases as where the separation occurred in the separated case. In each case (no pun intended) I could not detect any inside circumferential groove with the paperclip - the inside of each case at the separation area felt absolutely smooth with repeated tries. It could possibly be that such visually slight lines around the outside of the barrel of the cases toward the base could be a more sensitive test than the paperclip method. All comments are welcome.

Take a file and put a bevel on the end of the clip. A square end is less sensitive than a decent point.

The problem with using the line is that other things will cause lines: The rubbing on an ammo case, wear marks from bulging and resizing, etc.

I never understood why this would/has become a step in many peoples reloading procedure.

I find it's usually from following the manufacturer's setup procedure for the sizing die. Many state that the die should be set to contact the shellplate. This means over-bumping from square one.

 

[Charles]

I just carefully tried the paperclip method on those cases - tested 10-12 cases - all with the slight lines around the same area of the cases as where the separation occurred in the separated case. In each case (no pun intended) I could not detect any inside circumferential groove with the paperclip - the inside of each case at the separation area felt absolutely smooth with repeated tries. It could possibly be that such visually slight lines around the outside of the barrel of the cases toward the base could be a more sensitive test than the paperclip method. All comments are welcome.

you may want to cut one of the cases open and have a look inside its what helped me

 

[Triple BB]

Just cut one in half. I’d use a cut off wheel. The one in the pic looks like they hacked it with a jigsaw.

 

[NorCalMikie]

This topic is a good reason to get yourself a "broken case extractor" for EVERY caliber you shoot. Even had a couple custom made for my wildcat rounds.
NEVER had a bolt gun case head separate. M1A? YOU BET!!

 

[jelenko]

The line seems to be darn close to the case head. Could it be your sizing die which is stopping there?

That was my thought also. I've had my share of case separations but none that close to the head.

 

[K22]

Before everyone jumps off the cliff over full length resizing, if done properly it will not result in case head separation. This means measuring the bump with a bump gauge and caliper or the old fashion way using the rifle chambering method which admittingly is not as precise which in both instances, should result in only sizing enough so the case chambers with slight resistance i.e. .001 to .002" shoulder set back from the fire case's head space measurement.

Cases should be inspected every time before loading for defects including incipient head separation. In the latter case, the cause should be investigated before loading any more cases from that group. Almost always, there will be some signs before actual separation occurs but that's not absolute.

The only ones I ever saw were on a 300 Win Mag and on a 243 Win, the latter shot out of a 'break open' Thompson Center contender type action.

In both case I suspect the cause was over sizing but I can't say for sure except in the latter case since it happen to a friend of mine and I was able to help him investigate the problem. His break open action rifle had a large head space and he was sizing the cases using the die mfg.'s instructions which was resulting in pushing the shoulder back several thousands from a fire case's head space.

 

[acloco]

Cut apart the case that looks the worst. THIS will let you see what is happening.

Would like to see a larger picture or closeup. There may be another culprit at play here.