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Signs of case head separation after 5 firings?

S

SWThomas

Sergeant
Full Member
Minuteman
Jan 23, 2013
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Fort Lee, VA
#1
I'm using Lapua 30-06 brass and FL sizing it in a bushing die to give me 0.001-0.002 should bump. I'm firing it in a bolt gun. I noticed some abnormal marks on the case and decided to investigate. It was down toward the case head and only on about half of the case. I cut one open and sure enough, the precursor of a case head separation. I found 4 more that showed the same sign and culled them from the group.

Two questions: why am I seeing this after only 5 firings? And should I toss out the rest of the 5X fired cases from this lot?
 
#4
427Cobra said:
If your bumping minimally(.001ish) you will never ever never experience case head separation, you're primer pockets will be your case life killer
Click to expand...

Err, no.

I do Neck Only most of the time sizing, and after 35 reload cycles I did run into ICHSs, but never did loose a primer pocket; even with 47.8 gr Varget in 308 case!

Now if you can't get case life like I do, what you said has more than a grain of truth to it.

Back to the original posting: my guess is that you are sizing way more than 0.001 that you claim. I ran a test a few years ago, taking a set of cases that had been shot 5 times without any <body> sizing and tried to size them by 0.001". I failed. I could size them by 0.0016" and more, but when sizing at 0.0010 the brass simply sprung back without taking a size; case after case. Basically the yield point of the brass is such that it is still springy at 0.001 compression (i.e. under 48K PSI) but will yield at 0.0015+/- (greater than 48K PSI).
 
#5
Gunfighter14e2 said:
Bumping the shoulder has nothing to do with body/base sizing.


SW T
Check a fired case before resizing it, right where the pressure cut is forming, then resize it and recheck.
Click to expand...

Well I trash brass when the primer pockets become too loose, never once I have I had case head separation, I have brass with 30 loads fired, if the shoulder is bumped too much the result is case head separation. My advice is to get a headspace gauge, measure all your fired DECAPPED brass, set your FL die to bump the LONGEST measured case .001-.0015
 
#6
Measure 3 cases after they are fired, you will need a headspace gauge and a mic.
Also remove the primer with a decapper, without sizing.
Headspace, length, width at the base, width at pressure ring, width at datum line, width at neck etc.
Case wall thickness if you have the tools for it even.

Resize them and take the same measurements again, this should give you some very good indication as to what is going on.

Possible problems as i see it.
Wrong die adjustment, chamber with excessive headspace, die with out of spec dimensions witch happens at times, or simply a bad batch of brass witch can also happen.

Identify the problem, eliminate it and learn from the process.
It might be that culling your brass is just a waste of money, first off analyze the problem find the issue.
And then check your remaining cases wether they are worth holding on to.

Here is some detailed info on most of the process really:

The Rifleman's Journal: Basics: Measuring the Case

The Rifleman's Journal: Basics: Headspace

The Rifleman's Journal: Reloading: Case Head Separations


Now i do not shoot a 30-06 myself but i reload one for a friend.
Have a couple hundred 10 times fired Lapua cases, annealed every 3, headspace set back .001 with a redding body die, used with a stout load of N560 still in fully useable condition, your brass should not be trash after 5 firings if everything is normal.
 
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#7
427Cobra said:
Well I trash brass when the primer pockets become too loose, never once I have I had case head separation, I have brass with 30 loads fired, if the shoulder is bumped too much the result is case head separation. My advice is to get a headspace gauge, measure all your fired DECAPPED brass, set your FL die to bump the LONGEST measured case .001-.0015
Click to expand...

Yeah, I lose more brass due to attrition, lost in the rocks and the weeds than mechanical failure, maybe a 3 to 1 ratio?

And, the eventual mechanical failure is, (statistically) loose primer pockets, overwhelmingly, followed by an occasional split neck. Case head separation is virtually unknown to me. Well, yes I did have it once but the gunsmith was at fault. Virtually all this chatter about case head separation is caused by resizing mistakes. (opinion) BB
 
#9
SW:

I agree with another poster - 308 cases should last more or less forever. You are probably getting more bump than you want.

I had a hundred Lapua cases that I bought in the mid 1990s. I shot them pretty regularly since -- yeah, about 20 years. Last spring after buying a new die, I bumped the shoulders back by .015 on 20 cases and I had case head separations on every round. I kept the box to remind me.

If you put a fired case back into the gun and close the bolt, when the bolt starts to push the fired case shoulder into the chamber shoulder the bolt handle should have a little drag. This is easier to feel if you remove the firing pin assembly. Remove the firing pin, put the bolt into the gun, the bolt handle should drop freely. If you chamber one of the resized cases you made yesterday closing the bolt handle should feel almost the same - it should drop freely. You want that feeling but just barely.

When you put your sizing die into your press, use a feeler gauge and set it 0.010 above the shell holder. If you operate the press with nothing in it, the shell holder will not touch the die, it will stop .010 below the mouth of the die. Lube and size a case. Put it into the gun and close the bolt. The shoulder should not have been sized so it should feel just like the fired case in the paragraph above. Adjust the die and repeat the test until you can feel the bolt handle close without the case hitting the chamber. There are three strategies:

a. stepwise: adjust to 0.009. Resize that case. Repeat until you find the right spot.
b. split the difference: go from .010 to .005. If tight split the difference between 0 and 5, go to .003. If loose, split the difference between 5 and 10, go to .008 and repeat WITH A NEW CASE!
c. bigger steps: same as A except adjust in .002 steps. Do not use .003 steps.

I have a Dillon carbide 308 die. I use a Redding +.010 shell holder and set it either .014 or .013 above that shell holder to get a .001 bump. One of these days, I will get a lock nut that doesn't move :) This is the new die that I used to wreck those Lapua cases. It was completely my fault but if you buy one, be warned.
 
#10
bax said:
SW:

I agree with another poster - 308 cases should last more or less forever. You are probably getting more bump than you want.

I had a hundred Lapua cases that I bought in the mid 1990s. I shot them pretty regularly since -- yeah, about 20 years. Last spring after buying a new die, I bumped the shoulders back by .015 on 20 cases and I had case head separations on every round. I kept the box to remind me.

If you put a fired case back into the gun and close the bolt, when the bolt starts to push the fired case shoulder into the chamber shoulder the bolt handle should have a little drag. This is easier to feel if you remove the firing pin assembly. Remove the firing pin, put the bolt into the gun, the bolt handle should drop freely. If you chamber one of the resized cases you made yesterday closing the bolt handle should feel almost the same - it should drop freely. You want that feeling but just barely.

When you put your sizing die into your press, use a feeler gauge and set it 0.010 above the shell holder. If you operate the press with nothing in it, the shell holder will not touch the die, it will stop .010 below the mouth of the die. Lube and size a case. Put it into the gun and close the bolt. The shoulder should not have been sized so it should feel just like the fired case in the paragraph above. Adjust the die and repeat the test until you can feel the bolt handle close without the case hitting the chamber. There are three strategies:

a. stepwise: adjust to 0.009. Resize that case. Repeat until you find the right spot.
b. split the difference: go from .010 to .005. If tight split the difference between 0 and 5, go to .003. If loose, split the difference between 5 and 10, go to .008 and repeat WITH A NEW CASE!
c. bigger steps: same as A except adjust in .002 steps. Do not use .003 steps.

I have a Dillon carbide 308 die. I use a Redding +.010 shell holder and set it either .014 or .013 above that shell holder to get a .001 bump. One of these days, I will get a lock nut that doesn't move :) This is the new die that I used to wreck those Lapua cases. It was completely my fault but if you buy one, be warned.
Click to expand...

Thanks for the advice, but I'm not talking about 308. I'm experiencing this with 30-06 brass. I assume the procedures you laid out apply.
 
#11
Yep same procedure, same expectation. You typed 30-06 and I typed 308. Sorry, my bad.

Advantages -- it takes no extra tools except feeler gauges and either a tool or technique to remove the firing pin assembly. It makes no assumptions about your chamber or die. If you do it carefully, it is almost perfectly repeatable. If the nut on your die can be locked in place, you only have to do it once. You cannot use this procedure with straight-wall brass (but then you should not need to).

Here is another dodge. If you have a 40 S&W case, knock out the fired primer and drop it over the mouth of your 30-06 case - use it to measure the bump. Take a fired 06 case, drop the 40 case over the 06 case mouth, measure the length with your caliper. Resize your 06 brass. Repeat the measurement with the same 40 case. The second measurement should be ~ .001 or .002 less than the first one. Cheap. Easy. Works every time. Tooling (caliper and the 40 case) is typically available.

One caution, if you do step 1 above, that is unscrew the die by .010, size a case, and chamber it and if the bolt handle drops freely, you just found the problem. It means that you are pushing shoulders down by more than .010 and that is almost certain to cause case head separations. Now you have to work: get the gun headspaced using real headspace gauges. If the chamber is too long, you will have a gunsmith bill to buy a new bolt or refit the barrel, or you have a wall-hanger. If the chamber is okay then your die is too short - buy a new die. Dies are designed so that the correct head space is achieved when you push the press lever all the way down and the die just kisses the shell holder, with just detectable cam-over. If you have to raise the die above the shell holder (like I do with my Dillon) that is not the correct setup. I am getting good results with my Frankenstein setup but I may call Dillon and speak with them about a shell holder.
 
#12
I have had case head separations using .30-06 Lapua brass. Usually after 12-15 reloads. It's from bumping the shoulder too much. Like Mitch said it's really hard to just measure and bump .001".. I settle for .001-.002" of bump on the shoulders and call it good.

Or neck size, and bump shoulders when needed, but I chose to just full length size everytime and have reliable feeding.

It it might also be your chamber size is slightly larger than you sizing die. You might just be working the base of the case more without really knowing it...

the other thing to consider is whether or not your headspace is long in your chamber. On that initial firing your case will stretch quite a ways making the case wall thinner at the base. At it's already thinned condition after a few full length sizing you may get your case head separation.

I had a .30-06 rifle that had excessive headspace. I was losing brass from case head separation after 5 firings.

Easy to to check for with a set of gauges, or just measure a new piece of brass and a once or twice fired brass and compare the shoulder lengths.
 
#13
Lyman case length/headspace gauge.

Recognizing that not all chambers are created equal to the precise SAAMI spec, the proper H/S length is that which results in a small but perceptible bolt handle drag as the bolt handle is turned down to close.

Matching cases to SAAMI spec is good, matching it to the chamber in question is nearly always better.

I don't load .308, but I just ordered and received the Lyman gauge for .223 because I'm processing a lot of .223 brass these days. Fortunately a random check of my recently processed cases (from PPU match ammo) appears to be bang-on according to the gauge.

The rifle in question is a new Savage .223 11VT. This H/S corresponds to the RCBS F/L die screwed down to achieve light contact with the press baseplate. Normally, I would not resize that short, but the cases chamber with the slight drag I'm seeking.

Greg
 
Last edited:
#15
So I did some measuring...

Virgin Lapua measures 1.928" from the shoulder to the base, measured with a bump gauge and a caliper. My fired brass measures 1.934". So it had to grow 0.006" from its first use. I think I can rule out excessive headspace.

I measured the case where the others were showing separation signs and it they measured 0.468". This is with the blade tips of my caliper. After FL sizing it was pretty much the same, maybe 0.001" smaller depending on where I measured it.

I backed the die off and then slowly worked my way back down. I got to where I feel it's just kissing the shoulders and locked it down. I measured with my bump gauge the whole time I was adjusting. So I've got it set to where it's sizing the neck fine but it's not bumping the shoulders at all, according to my measurements.

Sounds like you guys were right and I was either over sizing or I got a bad batch of brass. I guess time will tell.

Does it sound like I got it figured out or should I check something else?
 
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#16
Only time will tell if you've solved the issue or not I suppose. It could be a number of things, but like suggested, it most likely had to do with excessive sizing/bumping of the shoulder.

Just curious though, what rifle is this being shot through? Something else to keep in mind is that some actions are just hell on brass.
 
#17
SWThomas said:
So I did some measuring...

Virgin Lapua measures 1.928" from the shoulder to the base, measured with a bump gauge and a caliper. My fired brass measures 1.934". So it had to grow 0.006" from its first use. I think I can rule out excessive headspace.

I measured the case where the others were showing separation signs and it they measured 0.468". This is with the blade tips of my caliper. After FL sizing it was pretty much the same, maybe 0.001" smaller depending on where I measured it.

I backed the die off and then slowly worked my way back down. I got to where I feel it's just kissing the shoulders and locked it down. I measured with my bump gauge the whole time I was adjusting. So I've got it set to where it's sizing the neck fine but it's not bumping the shoulders at all, according to my measurements.

Sounds like you guys were right and I was either over sizing or I got a bad batch of brass. I guess time will tell.

Does it sound like I got it figured out or should I check something else?
Click to expand...

I like the fact you started measuring stuff to the required precision.
I dislike that you fail to mention the post sized measurement--sloppy thinking processes.

Plus once you find the die setting that just fits the chamber, write it down so that a year (or 2000 rounds) from now you can measure it again to see if the chamber has grown from the constant banging (sic) going on.
 
#18
ZombieMonkey said:
Only time will tell if you've solved the issue or not I suppose. It could be a number of things, but like suggested, it most likely had to do with excessive sizing/bumping of the shoulder.

Just curious though, what rifle is this being shot through? Something else to keep in mind is that some actions are just hell on brass.
Click to expand...

It's a custom built Rem 700.
 
#19
MitchAlsup said:
I like the fact you started measuring stuff to the required precision.
I dislike that you fail to mention the post sized measurement--sloppy thinking processes.

Plus once you find the die setting that just fits the chamber, write it down so that a year (or 2000 rounds) from now you can measure it again to see if the chamber has grown from the constant banging (sic) going on.
Click to expand...

Which post size measurements do you mean? I said I set the die to where it's not bumping the shoulder so the measurement from shoulder to base is the same as it was before. Help me out here, I don't wanna be a slob.

Oh, and I do write down all my measurements.
 
#20
SWThomas said:
Which post size measurements do you mean?
Click to expand...

You started with:
Virgin Lapua measures 1.928" from the shoulder to the base, measured with a bump gauge and a caliper. My fired brass measures 1.934". So it had to grow 0.006" from its first use. I think I can rule out excessive headspace.
Click to expand...

And got to:
I backed the die off and then slowly worked my way back down. I got to where I feel it's just kissing the shoulders and locked it down. I measured with my bump gauge the whole time I was adjusting.
Click to expand...

Right here: what were the measurements?

So I've got it set to where it's sizing the neck fine but it's not bumping the shoulders at all, according to my measurements.
Click to expand...

What were these measurements?
 
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