Case Head Separation??

[JMD82]

While inspecting three different batches of brass, I ran a paper clip in a few cases and noticed a dip right before the case head. I went through each batch and picked one case from each that showed the most obvious sign that I believe could be case head separation. From what I have seen, I would suspect that the separation point would be higher up on the case wall and not as low as shown in the pictures. The exterior of the case shows a faint line, or should I say, a slight raised shoulder that goes all the way around the diameter of the case. From my understanding, the raised shoulder is caused by the resizing die. I could be wrong. Below are the details on my reloading process for case prep and history on the brass in question.

1. De-prime
2. Tumble to remove any and all debris from brass.
3. Anneal. Induction annealer at 4.5 seconds. Confirmed with 750 deg. Tempilaq.
4. Run brass through ring die if needed to avoid clickers. I do this every other reload. More on that below.
5. Resize with Wilson bushing die setting shoulder back .001-.002 thou using Redding comp shell holder set.
6. Trim to 2.005”, debur and chamfer case mouth.

Case 1 - Red batch. Lapua 308 win, Fired 9x, 178 gr ELDM, 44.7 gr Varget, 2770 fps range.

Case 2 - Blue batch. Lapua 308 win, Fired 9x, 178 gr ELDM, 44.7 gr Varget, 2770 fps range.

Case 3 - Orange batch. Lapua 308 win, Fired 3x, 178 gr ELDM, 44.7 gr Varget, 2770 fps range.

Powder charge is in the high node and heavy bolt lift / extractor marks are noticed at 45.5 gr. I might be a little hot.

All cases were fired in the same rifle, same barrel, chamber, etc with the exception of the orange batch. The first two firings were done in the same rifle as batch red and blue. Third firing on the orange batch was full length resized to min specs, and fired in a different rifle with fresh barrel and chamber. New rifle barrel length is shorter so at 43.5 velocity is in the 2640 fps range.

Circling back to step 4 on the sizing process. I found that the I.D. on my ring die is .465 which may be over working the base too much. I’m wondering if this is causing the so called separation above the case head. My ring die is a Lee 45ACP body die with a carbide sizing ring. It was an experimental thing discussed with a few that I thought I would try. I have since reached out to a fellow member here on this forum and inquired on his ring die which measures out at .468. My chambers were cut using a 308 Palma reamer and my smith likes them just a tad in the tight side. I don’t think my sizing die is knocking the base down enough, so I have to size the base every other reload.

Sorry for the long drawn out post. Just wanted make sure I got all the details out there.

Could this be case head separation?

Thanks
JMD82

 

[big5ifty]

IMO, this is not incipient [ beginning ] case head separation.

Your section is showing no cracks.

When the sharpened tip of the paper clip "catches" on the inside, it hooks in a crack.

It may be that your loads are over pressure, and your case rim is expanding too much.

If you have any virgin brass, measure just above the extractor rim with a 1/10,000 micrometer, then compare to the fired brass.

From Nosler :

• Lower pressure rounds, like the .30-30 Winchester, usually yield maximum pressures at .0003"-.0004" expansion.

• The .223 Remington, will show maximum pressure at .0004"-.0005".

• .308 Winchester, .270 Winchester, etc., typically yield .0005"-.0006" expansion at max pressure.

• Magnums, like the .300 Winchester Magnum, show maximums at .0006" -.0007" expansion, and should be measured on the belt.

 

[NorCalMikie]

Just in case, good reason to keep a "broken case extractor" in your range bag for EVERY caliber you shoot.
And, you might consider the type of sizing die you use. Full length with the neck button will pull the case longer with every upstroke.
I use bushing bump dies and after 25 to 30 resizes, no case head separations.
Shooting my M1A WILL show you thinning cases.

 

[K22]

Heavy bolt lift and ejector marks on the case head rim are almost always sure signs of over pressure.

I do not have a lot of experience with "case separations" since I've only seen incipient separations a few times and encountered it only once myself in all the years of reloading. The ones I have seen have been higher on the case than shown in your excellent pictures and had a thin "crack" like line around a portion of the circumference of the case.

Your pictures look like the classic case of a bulged case head which can occur with too high pressure and sometimes with a chamber that is not concentric. However, there is thinning at the base.

Perhaps some of the members with gunsmithing experience might chime it and offer expert opinions. I would continue to pursue this until you find the root cause and correct it.

 

[Tim Singleton]

Is this a bolt action rifle or semi?

Can you take the barrel off and drop a sized case in to see how much is protruding out of the chamber?
Pic 1 and 2 look to me like too much unsupported case head


This is exactly what the beginnings of case head separation looks like.
If the case is fully in the chamber you are oversizing this brass
one sign of this is the need to trim every sizing or even every other sizing
all that trimmed brass is coming from somewhere

 

[Old Navy]

This is what some of my 6.5X47L cased looked like after 18 firings. I scrapped them all. I saw three like these at 17. I scrapped them and inspected the rest. Saw several more with faint lines. When they start to show signs of separation they go fast.

 

[ShtrRdy]

What did you use to cut those cases open? Nice job!

Regarding the cross section - I would be concerned where the webbing has thinned down just above the bottom of the case cavity. I think something like this is due to a manufacturing defect.

 

[Ned Ludd]

As noted by others, it's not actually case head separation until the crack/split appears. Whether what you are observing will lead to case head separation is a harder question to answer. The expansion and re-sizing process causes the region of the case wall slightly above the webbing to get thinner, because it is an inherent weak spot with respect to longitudinal expansion/contraction. So that's just what cases do when we continually fire and re-size them. I am not seeing signs of what has correctly been called "incipient" case head separation in the pictures you showed, but that doesn't mean it isn't there.

One other thing that caught my attention was the the 44.7 gr of Varget. That's a lot of Varget for a fairly heavy bullet. Does the rifle have a relatively generous freebore for loading the 178s? From what barrel length are you achieving the ~2770 fps velocity from that load? If it's anything under 30", I would surmise that your running a pretty stout load, and it might be a contributing factor to the fact that you're having to re-size the base of the cases. Just something to consider.

One final note - it may be worth your time to sacrifice a couple pieces of brass that do not appear to show signs of incipient case head separation. Three pieces that appear to have a problem is a small sample size and having a piece or two that does not appear to be showing any issue for comparison might be worthwhile.

 

[Doom]

Assuming your Wilson Die is a FLS die you are growing your brass from the base on each firing and resizing. While setting a very small headspace helps prevent some longitudinal growth FLS brass will expand to fill the chamber which works to shorten the datum dimension as pressure builds then expands the case to fill the chamber completely. There is also a small amount of lengthening due to bolt thrust. As you resize you squeeze the case walls in which forces the datum longer which is then set back feeding brass to the neck and making it (he neck) longer. The closer the chamber dimension to the die dimension smaller the lengthening will be and the longer the brass will last.

If you are needing a ring die when firing the brass in the same rifle I would personally call that a pressure sign.

 

[markm87]

Where the red arrow is pointing in the first pic is not where I've ever seen a case separate. But rather where the sizing die base stops during resize (I believe).

 

[searcher]

When running high pressure loads, you are always going to get a "shiny" ring around the base of your brass from sizing. It will be fairly wide - like 1/4" or more. That does not translate to an impending case separation. That is your die pushing the case back into conformity. It is also normal to feel a very slight dip inside the case in that area after a number of firings. The signs of an impending insipient case separation are easily recognized by a VERY NARROW ring in the same general area, visible on the exterior of the case, yet is typically the width of a pencil line in a perfect circle around the case. When running a sharpened wire inside the case, there is no mistaking it when the wire falls into a sharp crevice. If you see either of these signs - your brass is toast.

 

[NorCalMikie]

Heavy bolt lift and ejector marks on the case head rim are almost always sure signs of over pressure.

If the short case can move in the longer chamber when fired, you'll get "ejector marks". Short (for the chamber) case gets fired, slams back against the bolt head and you get ejector marks.
Too hot a round will give you the same results. More so with short (for the chamber) brass.
First thing I would look at is the headspace. Not the chamber but the case size compared to the chamber. Whatever it is, make sure you're NOT pushing the shoulders back too far when resizing.
Too far back and the brass has to form to the chamber AGAIN and you start the thinning process of the case. Set up where the shoulder only gets pushed back maybe .001" and there's less movement when fired. You're not buying "off the shelf" ammo. Yours is custom made.
Headspace isn't an issue if you're only firing a few hunting rounds and not interested in reloading, just shooting.
When it comes to shooting, reloading and more shooting of the same brass over and over, the brass is the weak point. As mentioned previously, different style reloading dies can/will make a difference.
Short/snug headspace and different style dies will change everything.

 

[Chilly807]

I think the thin spots you are seeing near the web will be a problem at some point, if the case continues to thin in that area.

I've had several 223 cases exhibit a fine shiny ring around the middle of the case. In most of them it was a complete circle, in a few only a part circle. I think the difference in the 2 depends on when I noticed it.

One thing to note is that I could only see the ring on fired cases that hadn't been cleaned yet. Once they were cleaned and polished it was virtually invisible.

I had one case exhibit this, and it broke in 2 pieces when I tried flexing it in my fingers. It would probably have failed either on the next firing, or during the re-sizing process. It was a PMC case, I've stopped using them since then.

I've cut some apart when I first noticed it, and sure enough, there is a thinning of the case wall that coincides with the ring on the outside. Not cracked through quite yet, but not far away.

These are Lapua cases, the sectioned one was fired 18x, the whole one was 23x.

At that many firings, they don't owe me anything. I'll use brass until it gives me good reason not to. This is good reason, in my opinion.

It wasn't where I'd expect a case to separate, but it was interesting to note that it occurred right where the case started to transition to a thinner wall.
The PMC case failed in the same place, but after only 7 firings.

Once the Lapua brass is past about 10 firings, I make a point of checking the inside for low spots when they're processed.
I use a dental pick rather than a paper clip. It doesn't hook solidly as it would if there were a complete crack, but you can definitely feel the point dip into the thin area. That's my warning that the case is getting close to its life span.

I have some that are 25x fired with zero issues, other ones go in the recycle bucket at 15-16x. I think the newest was about 10x fired. No real rhyme or reason to it in my experience.

 

[Ned Ludd]

@Chilly807 posted some very good pictures of incipient case head separation (Post #13 above). You can clearly see that the deformation is occuring where the case wall transitions from the thicker region toward the case head into the relatively thin region that extends onward to the shoulder. The rather abrupt transition from thick to thin is an inherent weak spot when it comes to the longitudinal expansion/contraction the cases undergo during firing/re-sizing.

 

[JMD82]

Sorry for the late response everyone. Life finally slowed down long enough for me to read everyone’s feedback.

I’ll have to re-evaluate my process for sure. I’ve used the paper clip method in the past, but not that much. I’ll have to add that to my process and do it more often, especially on these cases for sure. I think the red and blue batch of cases are probably too far gone at this point, but I’ll keep a very close eye in them. The orange batch is not as bad, so those would be a good batch to monitor from this point forward to see if the changes I make have any impact.

I think the main thing I need to change is the powder charge. I’m just below my max at 44.7 gr. Max charge is 45.5 gr. I’ll admit I’m running these pretty hard being that close to max. I think that will make a big difference. I’m running these through a 24” Bartlein at the moment.

@Chilly807, Thanks for the detailed pics.

Once again, thanks everyone for the feedback and recommendations. It is very helpful.

JMD82

 

[Doom]

With regards to @Ned Ludd I had some time to go back and look at your load in GRT and 44.7 gr puts you at 64.6ksi and 2749 fps. You are defiantly overpressure so your brass life is going to pay the price. I would back off to the 43.5 gr (59ksi) region as a minimum and if it were me I would be looking in the 41.8 to 42.5 gr (54.7 psi) area. It's going to cost you about 50-60 fps per grain but your brass life should increase significantly.

I also think that you are oversizing your brass. How did you determine your maximum datum dimension?

 

[Rook 6]

Lots of good info being provided here. But I think a level set might be worthwhile…. All cases, regardless of how heavy a load is, will thin along the webline. All annealing, minimal sizing/moving of brass does is slow down the process and extend brass life. Understand that all efforts will slow, not stop the thinning process. Just keep running something along the inside of the case to make sure the dip in the ring doesn’t get too deep. For me personally on high powered rounds, you get your money’s worth after around ten firings. Less with heavy loads. After that, I toss it and start a new lot. The juice ain’t worth the squeeze at that point and not worth the risk. YMMV.

 

[SKWERLZ]

I think the thin spots you are seeing near the web will be a problem at some point, if the case continues to thin in that area.

I've had several 223 cases exhibit a fine shiny ring around the middle of the case. In most of them it was a complete circle, in a few only a part circle. I think the difference in the 2 depends on when I noticed it.

One thing to note is that I could only see the ring on fired cases that hadn't been cleaned yet. Once they were cleaned and polished it was virtually invisible.

I had one case exhibit this, and it broke in 2 pieces when I tried flexing it in my fingers. It would probably have failed either on the next firing, or during the re-sizing process. It was a PMC case, I've stopped using them since then.

I've cut some apart when I first noticed it, and sure enough, there is a thinning of the case wall that coincides with the ring on the outside. Not cracked through quite yet, but not far away.

These are Lapua cases, the sectioned one was fired 18x, the whole one was 23x.

At that many firings, they don't owe me anything. I'll use brass until it gives me good reason not to. This is good reason, in my opinion.

It wasn't where I'd expect a case to separate, but it was interesting to note that it occurred right where the case started to transition to a thinner wall.
The PMC case failed in the same place, but after only 7 firings.

Once the Lapua brass is past about 10 firings, I make a point of checking the inside for low spots when they're processed.
I use a dental pick rather than a paper clip. It doesn't hook solidly as it would if there were a complete crack, but you can definitely feel the point dip into the thin area. That's my warning that the case is getting close to its life span.

I have some that are 25x fired with zero issues, other ones go in the recycle bucket at 15-16x. I think the newest was about 10x fired. No real rhyme or reason to it in my experience.

Those are more indicative of the case head separations I’ve seen.

 

[Webster]

While inspecting three different batches of brass, I ran a paper clip in a few cases and noticed a dip right before the case head. I went through each batch and picked one case from each that showed the most obvious sign that I believe could be case head separation. From what I have seen, I would suspect that the separation point would be higher up on the case wall and not as low as shown in the pictures. The exterior of the case shows a faint line, or should I say, a slight raised shoulder that goes all the way around the diameter of the case. From my understanding, the raised shoulder is caused by the resizing die. I could be wrong. Below are the details on my reloading process for case prep and history on the brass in question.

1. De-prime
2. Tumble to remove any and all debris from brass.
3. Anneal. Induction annealer at 4.5 seconds. Confirmed with 750 deg. Tempilaq.
4. Run brass through ring die if needed to avoid clickers. I do this every other reload. More on that below.
5. Resize with Wilson bushing die setting shoulder back .001-.002 thou using Redding comp shell holder set.
6. Trim to 2.005”, debur and chamfer case mouth.

Case 1 - Red batch. Lapua 308 win, Fired 9x, 178 gr ELDM, 44.7 gr Varget, 2770 fps range.

Case 2 - Blue batch. Lapua 308 win, Fired 9x, 178 gr ELDM, 44.7 gr Varget, 2770 fps range.

Case 3 - Orange batch. Lapua 308 win, Fired 3x, 178 gr ELDM, 44.7 gr Varget, 2770 fps range.

Powder charge is in the high node and heavy bolt lift / extractor marks are noticed at 45.5 gr. I might be a little hot.

All cases were fired in the same rifle, same barrel, chamber, etc with the exception of the orange batch. The first two firings were done in the same rifle as batch red and blue. Third firing on the orange batch was full length resized to min specs, and fired in a different rifle with fresh barrel and chamber. New rifle barrel length is shorter so at 43.5 velocity is in the 2640 fps range.

Circling back to step 4 on the sizing process. I found that the I.D. on my ring die is .465 which may be over working the base too much. I’m wondering if this is causing the so called separation above the case head. My ring die is a Lee 45ACP body die with a carbide sizing ring. It was an experimental thing discussed with a few that I thought I would try. I have since reached out to a fellow member here on this forum and inquired on his ring die which measures out at .468. My chambers were cut using a 308 Palma reamer and my smith likes them just a tad in the tight side. I don’t think my sizing die is knocking the base down enough, so I have to size the base every other reload.

Sorry for the long drawn out post. Just wanted make sure I got all the details out there.

Could this be case head separation?

Thanks
JMD82
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In Tony Boyer’s book p. 111 he says clicker brass is caused by excessive work hardening of the brass body. I think he says he tosses the brass if he gets clickers. You definitely have hot loads if there is an increase in effort to lift the bolt. Why does everyone want to put as much powder in a case that they can get away with? Don’t understand the use of a 45 ACP die. You may be trying to size down the body that you expaanded with hot loads. If you get a FL bushing die made for your caliber and size the cases for about 2-3 thou shoulder bump and don’t shoot hot loads you should be OK.

Different manuals have different max loads.
Based on my Berger and Sierra loading manual all your charges are over max for a 308.

Berger manual 175 gr bullet 43.0 gr Varget max. Your at 44.7 gr.
Sierra manual 175 gr bullet 41.7 gr Varget max. Your at 44.7 gr.
You said you even tried 45.5 gr of Varget and thought it might be a ittle hot!!!! Back of 1-2 gr and size properly with a FL bushing die and you problems will go away.

I have reloaded my 6BR cases over 20 times without a problem. I probably tossed 3 for cracked necks in 10 years. I didn’t always anneal. I shot a 7mm Rem Mag off a bench for ten years without case problems. Don’t remember ever having to toss a case with a body defect. I have been reloading since 1979 and never had a case problem. You don't understand how to make safe loads.

 

[209jones]

The pic posted of the groove being down in the web, does strike me as a weird location, they usually form at the "tip" of the web from what I've seen, or a bit higher. I guess anything is possible.