What is this???

[JDBraddy]

I fired a round yesterday, and noticed smoke from around the bolt, it was difficlut to lift the bolt handle, then the case came out in two pieces (see picture below). This was not a hot load, 7mm-08, 150gr SMK, 42gr Alliant 2000-MR, Fed-210 primer, 2.800-OAL, Remington brass, chronographed at 2,634fps. When I went home, I examined the brass, it looked like it had been cut in half with a band-saw. I looked at the rest of this lot of brass. It's not new brass, it started out as factory ammo, and has been fired and reloaded six or seven times. Out of a hundred pieces, I found about twenty that had a visible ring of discoloration at about the same point where the seperation occured. I've been reloading almost thirty years now, and have never encountered this before, what is it?

 

[vicvanb]

Looks like a classic case head separation? Check for excessive headspace with a "no go" headspace gauge. Do not fire any more rounds using this bunch of brass until you check headspace.

 

[Boyd Allen]

I am just guessing but what you probably have there is the cumulative effects of setting your cases shoulders back too far when sizing them. The ones with the bright lines probably have a corresponding groove inside the cases, that can be detected by straightening a large paper clip, and bending a short (.1") right angle at one end to be able to feel the groove. If I am correct, you need to set about learning how to set your FL die properly. At some point you will probably get some advice on how to do this by feel. I disagree with this approach because it assumes that the die is properly dimensioned for the chamber that the brass was fired in. The approach that I recommend is that you use the correct tool and measure how much shoulder "bump" your die is set for. Something on the order of .001 to .002 from a tight case should be about right. Using a once fired case, putting the shoulder of a sized case at the same distance from the case head as it came out of the chamber may work just fine. When you measure fired cases, either deprime the case first, or reseat the primer so that it is well below flush.

 

[JDBraddy]

I am just guessing but what you probably have there is the cumulative effects of setting your cases shoulders back too far when sizing them. The ones with the bright lines probably have a corresponding groove inside the cases, that can be detected by straightening a large paper clip, and bending a short (.1") right angle at one end to be able to feel the groove. If I am correct, you need to set about learning how to set your FL die properly. At some point you will probably get some advice on how to do this by feel. I disagree with this approach because it assumes that the die is properly dimensioned for the chamber that the brass was fired in. The approach that I recommend is that you use the correct tool and measure how much shoulder "bump" your die is set for. Something on the order of .001 to .002 from a tight case should be about right. Using a once fired case, putting the shoulder of a sized case at the same distance from the case head as it came out of the chamber may work just fine. When you measure fired cases, either deprime the case first, or reseat the primer so that it is well below flush.

I'm using an RCBS full length die, I used an RCBS micrometer to measure, and adjusted the die to where it bumps the shoulder back about three thousanths of an inch on a fired case. The case necks have been turned to a thickness of 12 thousanths of an inch.

 

[Boyd Allen]

Try a little experiment. Neck size a case, and fire it, repeating the process several times until its "headspace no longer increases. Do all measuring with the primer removed. Next use that measurement to bump its shoulder back .001 and compare that length to what you have been sizing to. I think that you have probably been setting your shoulders back too far, because the fired cases that you have been comparing to were only fired once and were not tight in the chamber, from shoulder to head. Generally when setting up a FL die from once fired brass, I set the shoulders so that they are the same as the fired case. With the reduction in body diameter from sizing, they usually chamber just fine. Bumping any amount from once fired is usually unnecessary. I ran into this issue for the first time when FL sizing for a .220 Swift. If I bumped at all, there would be a bright ring near the head. If I set the die to duplicate how once fired cases came out of the chamber, the problem no longer occurred. Shoulder angle, and annealing get into this too.

 

[JDBraddy]

Try a little experiment. Neck size a case, and fire it, repeating the process several times until its "headspace no longer increases. Do all measuring with the primer removed. Next use that measurement to bump its shoulder back .001 and compare that length to what you have been sizing to. I think that you have probably been setting your shoulders back too far, because the fired cases that you have been comparing to were only fired once and were not tight in the chamber, from shoulder to head. Generally when setting up a FL die from once fired brass, I set the shoulders so that they are the same as the fired case. With the reduction in body diameter from sizing, they usually chamber just fine. Bumping any amount from once fired is usually unnecessary. I ran into this issue for the first time when FL sizing for a .220 Swift. If I bumped at all, there would be a bright ring near the head. If I set the die to duplicate how once fired cases came out of the chamber, the problem no longer occurred. Shoulder angle, and annealing get into this too.

I also posted this on AccurateShooter.com, got similar advice. Will use the cases with a visible ring to reset my sizing die to bump the shoulder a 0.001" or less, then discard them, and will also take the rifle to a gunsmith tomarrow, to have the headspace on the rifle checked. Then reload the remaining brass without a visible ring and see what happens. Every once in a while, even us old dogs have to learn a new trick!
Thanks,
JDBraddy

 

[alinwa]

Doesn't matter what the headspace is, bumping the shoulder back .003 WILL cause casehead separation within just a few firings. It has to, it's simple mechanics.

there's nothing "wrong with" your gun


al

 

[Dick Grosbier]

Doesn't matter what the headspace is, bumping the shoulder back .003 WILL cause casehead separation within just a few firings. It has to, it's simple mechanics.

there's nothing "wrong with" your gun


al

Gotta agree with Al on this one, .003" is way too much shoulder setback. I learned this the hard way by ruining a group of 30x47 Lapua brass, only difference my ring and separations were closer to bolt face.
Dick

 

[JDBraddy]

I measured each, and chose five of the longest cases, each chambered in the rifle without resistance, so I set the sizing die so that it touches but does not bump the shoulder at all, in fact a couple of these cases actually grew a thousanth longer when sized, I assume because of the neck expantion ball pulling upward on the inside of the neck/shoulder junction as the case was extracted from the die. I then resized all the cases and they are in the tumbler removing the lube now. Unfortunately, I work all weekend, so will have to wait till next week to load an fire them again.

 

[alinwa]

............ a couple of these cases actually grew a thousanth longer when sized, I assume because of the neck expantion ball pulling upward on the inside of the neck/shoulder junction as the case was extracted from the die..

Well, kinda'........ try this, next time the kids have some of them skinny animal-making balloons around squeeze one in the middle and watch the ends pop out.

Cases act the same way when you squish 'em.

al

 

[Dick Grosbier]

I measured each, and chose five of the longest cases, each chambered in the rifle without resistance, so I set the sizing die so that it touches but does not bump the shoulder at all, in fact a couple of these cases actually grew a thousanth longer when sized, I assume because of the neck expantion ball pulling upward on the inside of the neck/shoulder junction as the case was extracted from the die. I then resized all the cases and they are in the tumbler removing the lube now. Unfortunately, I work all weekend, so will have to wait till next week to load an fire them again.

I hope you realize you need to start with new brass at this point. All your brass even the ones you do not see a line on are compromised.That is assuming they have already been pushed back .003 " and fired.

 

[Boyd Allen]

The reason that your cases' headspace grew is that the diameter of the body had been reduced, which squeezed the shoulder forward, and the die had not been set low enough to push it back to where it started. It has nothing to do with expander pull. Also, remember that one turn of a die equals .071" of up or down movement in the press threads, so make your moves VERY small when approaching your final setting. Once you are there, you can take a feeler gauge reading between die and shell holder and record that , and the next time you set the die up shorten the task by setting it up with a gauge that is a couple of thousandths thicker. Yes, you do need to ashcan the brass and start over. If you do as I suggested and neck size a case till it gets tight, you can use it for a reference to set bump accurately. Also, as the other poster mentioned, don't bother to have your headspace checked. The simple truth is that many reloaders do not know about properly setting up a FL die for a particular rifle. With a little practice and attention to detail, you will soon have the routine down pat.

 

[vicvanb]

Also, as the other poster mentioned, don't bother to have your headspace checked.

The first post said nothing about bumping the shoulder excessively. It was therefore reasonable to assume the problem was with the rifle, not the brass as a result of reloading techniques.

Some rifles do have excessive headspace. Adjusting the sizing die can prevent case head separations but the next owner of the rifle may not be aware or may not reload. He needs to know about headspace problems if they exist. Gas coming back through the action is not fun.

 

[alinwa]

The first post said nothing about bumping the shoulder excessively. It was therefore reasonable to assume the problem was with the rifle, not the brass as a result of reloading techniques.

Some rifles do have excessive headspace. Adjusting the sizing die can prevent case head separations but the next owner of the rifle may not be aware or may not reload. He needs to know about headspace problems if they exist. Gas coming back through the action is not fun.

Not reasonable, faulty reasoning throughout. The rifle DOES NOT have "excessive headspace."

vic, I and others DEDUCED the problem from the results.........I realize this makes no sense to you,

I can't help that.

al

 

[R.DesJardin]

Case failure

The first post said nothing about bumping the shoulder excessively. It was therefore reasonable to assume the problem was with the rifle, not the brass as a result of reloading techniques.

Some rifles do have excessive headspace. Adjusting the sizing die can prevent case head separations but the next owner of the rifle may not be aware or may not reload. He needs to know about headspace problems if they exist. Gas coming back through the action is not fun.

This is true. I have seen a few factory rifles suffer from max headspace and some factory ammo was scary to shoot. Size the case to fit the chamber.
The common cause is from excessive oversizing as stated previously. There are a few rifles that were harder on cases and saw more of this, one is the Rem 788, the rear lug design allows for more case stretch since the length of the receiver can stretch.
The failure point is directly related to the forming/drawing process tooling, this does vary from case to case of course. I would typically call this a case stretch failure.

 

[alinwa]

This is true. I have seen a few factory rifles suffer from max headspace and some factory ammo was scary to shoot. Size the case to fit the chamber.
The common cause is from excessive oversizing as stated previously. There are a few rifles that were harder on cases and saw more of this, one is the Rem 788, the rear lug design allows for more case stretch since the length of the receiver can stretch.
The failure point is directly related to the forming/drawing process tooling, this does vary from case to case of course. I would typically call this a case stretch failure.

huhh??

The failure point is directly related to the forming/drawing process tooling, this does vary from case to case of course.

What does this mean???......are you implying that the cases failed where they did because of how they were made?

And what could be "scary" about max headspace? Misfires???

Good grief, give the man some rationale...

And as I've understood it 788's suffer from bolt collapse due to the rear lugs, not because "the receiver can stretch."

People come here to learn, not to be told to "you can't be too careful" and given no reasons for the failures....

Please, for starters, explain how to "size the case to fit the chamber" so as to HELP the op, not confuse him.

al

BTW, the reason I'm obsessed with helping people instead of shunting them off to the doctor for meaningless tests is because I really DO have an ulterior motive, to save the planet. efficiency, efficiency, efficiency. "Checking the headspace" on the op's gun costs a hunnerd dollars against our resources, a hunnerd dollars WASTED from bad advice.

"It Couldn't Hurt" is the bane of my existence.

checking the headspace "just to be sure" is a waste of resources...

 

[Wilbur]

Dick said it nicely but I'll repeat the concept. Don't shoot the pictured cases again - ever.

 

[vicvanb]

The rifle DOES NOT have "excessive headspace."

And you claim I used faulty reasoning.

Without checking headspace, no one (including you) can state that the rifle has no problem.

Bumping the shoulder back 0.003 (not revealed in the first post I replied to) likely contributed to case head separations but no one can conclude this was the sole cause absent a headspace check.

You imply excessive headspace is no problem. Very bad advice possibly resulting in injury to the rifle's next owner who may be unaware.

And $100 to check headspace? It's a 2 minute chore to run the gauge in the chamber. Those I know would do it for no charge.

 

[Centerfire]

For what it is worth

Forster Products lists the Go, no go, and field gages for this 7mm-08.
You could contact them for a price.
I'm sure Brownells offers something similar.
Centerfire

 

[Bill Dorsey]

I've had the same thing happen for no other reason than the brass got old and brittle.

One piece let go and others followed in a similar manner.

Solution is simple......replace your brass and make sure nothing has changed in your reloading setup.

I've seen enough variations in shell holders....as much as 4 thousandths...... to cause the problem discussed.

My solution was to measure then color code my shell holders and my dies.....just to make sure I was using the correct one.


Just running a go /no-go gauge in the chamber doesn't answer all the questions as to why something like that happened.

Likewise......it isn't usually a freebie.....shop time is worth money.