Signs of case head separation?

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rf2

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Does the appearance of a ring close to the case head always mean that case head separation is about to occur?

I was at the range on the weekend firing off some handloads for my K31 (7.5X55 swiss). I used Norma brass that I obtained by firing some newly purchased Norma Oryx cartridges, so the brass was once-fired (in my own gun). I put together some loads that were below the maximum recommended load, and after firing them, I noticed that there seemed to be signs of "incipient case head separation" (term used in my Lyman manual), that is to say, a bright ring seems to be starting at the point where the case wall joins the case head. On some of the brass, the ring is almost all the way around the case. There are no signs of excessive pressure on the brass (primers are fine, extraction was normal, no impressions on the case head). As recommended by several sources, I used a piece of wire to feel around on the inside of the case where the ring appears to be forming, but I can't really feel anything obvious in any of the cases that would indicate that there is a problem, but I am not really sure how obvious it should be.

K31s are not know to have headspace issues, and all numbers are matching, so I really didn't expect to ditch brass after the second firing. Could it be that I am just overly paranoid, or could the brass really be ready to separate at the case head? It did seem like the Norma Oryx was loaded pretty hot - my handloads, and GP11 were impacting 2 MOA low compared to the factory Norma Oryx cartridges. Could this be contributing to the problem, or would it be solely a headspace issue?

I also measured the diameter of the head for the Norma brass and compared it the the diameter of once-fired GP11 brass. The diameter of the Norma brass is 0.006" smaller, so I am wondering if the extra bit of diameter in the chamber is contributing to the problem.


Here are some pictures of the brass:
IMG_2369.jpg

IMG_2370.jpg

IMG_2374.jpg
 
The line if how far the case sits inside the chamber. The 2 inch difference in you POI can be contributed to bullet weight, velocity and barrel harmonics. Reload them and carry on.
 
That looks like the mark from a sizing die, not case head separation. But to be on the safe side bend a paper clip and check the inside of the case for a ring.
 
Yep, that ring is left by the sizing die, which is normal. The ring that indicates an impending head separation is higher, brighter and more sharply demarcated. If you have doubts, screw the unreliable paper clip test, sacrifice a case by splitting it lengthwise and looking at the inside. Or just load and shoot them. Case head separations are not the dramatic failure people seem to think they are.
 
BattleRife said:
Case head separations are not the dramatic failure people seem to think they are.
Click to expand...
There have been a few pics of destroyed Norc M305's that where a result of case head separation. I believe there where also a couple pics of AR's that where somewhat damaged because of one.

I read somewhere that the M1A/M14/M305 design starts to extract the case when the pressure is still quite high in the chamber (higher than normal for a semi at any rate). If that's true then a case head separation could cause quite a problem.

In any non semi rifle you are correct, they are just an annoyance. I've had probably 4 case head separations in my No.1 Mk.3 in the past year or so with nothing but a dirty chamber as a result. In a K31 it wouldn't be an issue and worst realistic case scenario you will have some gas blow back out of the bolt (wear shooting glasses!) and have a pain of a time getting the broken off top of the case out.
 
As others have said check the inside of the case to be sure but i would say no it isn't a head seperation. You could destroy a case if your so inclined but the wire with a small 90 degree bend will tell you if it is starting to seperate.
 
Take a closer attention to your new/once fired brass - meaning examination, before and resizing. As already said above, they do look resizing marks.
If a doubt remains in your mind, use a small pick and see if you can feel for an internal recess where the ring is (the paper clip check). I like clear evidences and eliminate doubts so I would put a cutting disk on my dremel and cut the "worse" case in 2 halves lengthwise to see and measure depth.
Let us know of your findings.
Cheers
 
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Google is your best friend, I Googled "Signs of case head separation?" and then clicked on "images" at the top of the page.

http://www.google.com/search?hl=en&...urce=og&sa=N&tab=wi&ei=HOFFUezJIInk4AOjsoDQBw

Then the same thing but just "case head separation".

http://www.google.com/search?hl=en&rlz=1C2KMZB_enUS524US524&q=Signs+of+case+head+separation%3F&bav=on.2,or.r_qf.&bvm=bv.43828540,d.dmg&biw=1024&bih=655&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=HOFFUezJIInk4AOjsoDQBw#um=1&hl=en&rlz=1C2KMZB_enUS524US524&tbm=isch&sa=1&q=case+head+separation&oq=case+head+separation&gs_l=img.12..0j0i24l4.48236.51317.0.53445.2.2.0.0.0.0.94.172.2.2.0...0.0...1c.1.6.img.LGNk9_lMP1s&bav=on.2,or.r_qf.&bvm=bv.43828540,d.dmg&fp=547a0bc75bbbe607&biw=1024&bih=655

I don't use a bent paper clip and can measure case stretch and thinning in the web in thousandths of an inch.

RCBSCMG.jpg


Case head separations.

308fail-1.jpg


308fail2-1.jpg
 
Cleftwynd said:
That looks like the mark from a sizing die, not case head separation. But to be on the safe side bend a paper clip and check the inside of the case for a ring.
Click to expand...

This. Once you know what a thinning case feels like with a paperclip, you case find pending seperations long before they show up on the outside of the case.
 
Thanks for the info folks. I'll probably cut one open just to be sure, but I will also pay closer attention next time I size newer cases. I'm almost sure though that the marks were not there before sizing EDIT: firing
 
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So I tried full length sizing another once fired case, and while I could see some faint signs of where the die sized near the case head, the marks were no where near as obvious as in the photos I posted earlier.
I then cut one of the cases in half, and I cannot see any thinning of the case wall in the area where the ring appears. I guess the cases can be used for further reloading. I'll post pics sometime soon for those that are curious
 
I know its a different caliber all together but I normally get 5-6 full house loads from winchester brass in my 30-06. I found federal brass to be almost one time use and hornady not alot better. No issues with winchester or rem brass so far.
 
hometownhero said:
I know its a different caliber all together but I normally get 5-6 full house loads from winchester brass in my 30-06. I found federal brass to be almost one time use and hornady not alot better. No issues with winchester or rem brass so far.
Click to expand...


I have discovered that Nosler brass in 30-06 is too soft for many loads as well, primer pockets get loose with mild loads. However the 325 WSM Nosler brass seems excellent.

I wish Nosler would tell you exactly where that lot of brass was made, ie... Winchester, Remington, Federal, Norma, etc....
 
A case head separation ring, when seen from the outside of the case, looks very shiny and we usually can see a difference in structure configuration when magnified (the surface does not look unifrorm).
The ring usually is a sign of too much headspace which can be the result of too much resizing. It can also happen after too many resizing.
 
rf2 said:
So I tried full length sizing another once fired case, and while I could see some faint signs of where the die sized near the case head, the marks were no where near as obvious as in the photos I posted earlier.
I then cut one of the cases in half, and I cannot see any thinning of the case wall in the area where the ring appears. I guess the cases can be used for further reloading. I'll post pics sometime soon for those that are curious
Click to expand...

Here are the pictures of the cut case:
IMG_2393.jpg

IMG_2383.jpg
 
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