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I am wondering what would cause a case to seperate 11/16" up from the base. The case will seperate I know on the expansion ring if stretched too much or from excess head space.
Case Seperation
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3,792 Posts
What brand case and caliber? I've seen Federal 308 seperate there on numerous occasions and have refused to use them since then.
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6mm Rem, Rem Brass. Reloaded twice.
Besides a rare defect in the brass of that case the most common reason for web thinning at the expansion web is excessive headspace. That excessive headspace can be caused by a chamber thats oversize or FL sizing the brass too far.
Set your FL so that it does not oversize the brass. So many think that they need to set the FL die to hit the shell holder. Don't do it that way. Set the die so that you can feel the case's shoulder just touch when closing the bolt.
Of course that round then may not fit another chamber of the same 'caliber'.
Make a feeler wire with a tiny 90 degree bent hook at its end. Reach into every case and feel for a insipiant head separation.
Set your FL so that it does not oversize the brass. So many think that they need to set the FL die to hit the shell holder. Don't do it that way. Set the die so that you can feel the case's shoulder just touch when closing the bolt.
Of course that round then may not fit another chamber of the same 'caliber'.
Make a feeler wire with a tiny 90 degree bent hook at its end. Reach into every case and feel for a insipiant head separation.
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92 Posts
What I am asking is why the case seperated 11/16" up the case, NOT at the expansion ring. There are other cases with the ring in the same place that will seperate if fired I believe.
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3,792 Posts
all is not lost Foster. Just have your local 'smith check the headspace and then you might get the info about whether it's the gun or brass.
Re-cutting a chamber isn't a big deal, but you can also fix a headspace problem with some careful reloading techniques if you don't want a 'smith cutting on a new chamber.
Re-cutting a chamber isn't a big deal, but you can also fix a headspace problem with some careful reloading techniques if you don't want a 'smith cutting on a new chamber.
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14,549 Posts
George,
Just to be clear, you're saying these broke where the brass is thinner than it is where the case wall meets the head where the pressure ring normally forms by thinning? I've seen foreign brass that was thick further up the case than normal, so the pressure ring forms forward of the normal position. They were either Privi Partisean or Sellier and Bellot, I think?
Rocky may know more about the industry details, but I understand Remington now contracts out at least some of their brass and bullets to foreign makers, so there is some catch as catch can involved with quality. On another forum a fellow described complaining to Remington that two batches of Remington bullets he got had 0.001" different diameters even though the boxes were marked the same, and Remington told him they couldn't be expected to stock two kinds of boxes for an otherwise identical bullet. Right. These were pistol bullets apparently coming from different contractors, one of whom seems likely to be challenged at making English to metric conversions. Lowest bids can sometimes do that for you.
If you have more cases from the same lot, I would send Remington a broken and an unbroken one and let them look at them. If you have the original packaging with a lot number, give them that, too. Tell them the load you used in it. They may replace it? They should be made aware they are getting bad brass from the source of that lot, whether they replace it or not.
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Just to be clear, you're saying these broke where the brass is thinner than it is where the case wall meets the head where the pressure ring normally forms by thinning? I've seen foreign brass that was thick further up the case than normal, so the pressure ring forms forward of the normal position. They were either Privi Partisean or Sellier and Bellot, I think?
Rocky may know more about the industry details, but I understand Remington now contracts out at least some of their brass and bullets to foreign makers, so there is some catch as catch can involved with quality. On another forum a fellow described complaining to Remington that two batches of Remington bullets he got had 0.001" different diameters even though the boxes were marked the same, and Remington told him they couldn't be expected to stock two kinds of boxes for an otherwise identical bullet. Right. These were pistol bullets apparently coming from different contractors, one of whom seems likely to be challenged at making English to metric conversions. Lowest bids can sometimes do that for you.
If you have more cases from the same lot, I would send Remington a broken and an unbroken one and let them look at them. If you have the original packaging with a lot number, give them that, too. Tell them the load you used in it. They may replace it? They should be made aware they are getting bad brass from the source of that lot, whether they replace it or not.
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92 Posts
Here is the story, I had a gunsmith rebarrel a Rem 700 with a Douglas 6mm Rem barrel. I have to overcam the die by 1/4 turn to even get the case to fit into the chamber. I have tried factory new cases and the don't fit. I personally feel the chamber could be cut short but I don't know. I have approximately 100 rounds through the barrel. I took the rifle to the gunsmith last Tuesday after a round seperated in it. He has it now as he said he didn't know what could cause the problem.
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12,515 Posts
Sounds to me like it's short chambered and if that smith doesn't know what's wrong, you need to take it to a different smith.
Is the smith you took it to the same one who did the original rebarrel?
RJ
Is the smith you took it to the same one who did the original rebarrel?
RJ
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92 Posts
recoil junky,
You are thinking the same thing as I am about the short chambering. Yes it is the same gunsmith as I feel if it is the chamber he should fix it, I asked specifically if he chambered the barrel or got it short chambered. He told me he chambered it. When I took it down last Tuesday is when he told me he didn't know what would cause it, this was just standing there talking to me without getting the case out of the chamber or anything.
You are thinking the same thing as I am about the short chambering. Yes it is the same gunsmith as I feel if it is the chamber he should fix it, I asked specifically if he chambered the barrel or got it short chambered. He told me he chambered it. When I took it down last Tuesday is when he told me he didn't know what would cause it, this was just standing there talking to me without getting the case out of the chamber or anything.
Think like RJ and yourself that the chamber is short. Ask him to run the reamer and finishing reamer in again just to be sure. If he isn't inclined to do that, take it to another 'smith and ask for the above. Also, at the new 'smith, ask for headspacing check.
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92 Posts
I talked to my gunsmith a bit ago and he has found the problem and fixed it. It seems the diameter of the chamber was the bare minimum SAMMI measurement, the length was okay.
He polished the chamber to the proper diameter so it should be okay.
He polished the chamber to the proper diameter so it should be okay.
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92 Posts
http://www.larrywillis.com/techtips.html
Go /No-go Gauge
This is what a set of .308 Winchester Go/No-go gauges look like. They are designed to verify that chamber headspace is within the SAAMI spec tolerance from the base of a case to its shoulder. It's best to use them after removing the ejector on most rifles, so that you can "feel" these gauges as they are chambered. These gauges help you verify that any factory loads should fit in your chamber, and be safe to fire.
When reloading, it is important to always bump the shoulder of your cases back at least .001" - .002" to ensure a reliable fit in your chamber. There is no accuracy gained by crushing a cartridge into your chamber. This affects the concentric alignment in a negative way, and it can wear the lugs of your bolt. Keep in mind that most necked cases are tapered, and the wall of your case should never press against the chamber.
Not all chamber reamers are perfect; and as they begin to wear out, they will cut tighter chambers. A set of these Go /No-go gauges will rarely detect the work from a defective or worn chamber reamer. This is because headspace gauges can't check the width of a chamber.
I have examined custom chambers that checked out perfectly fine with Go /No-go gauges, but these chambers had "excessively" tight body diameter. Match chambers are always a bit tighter at the neck and usually require handloaders to do some neck turning, but the rare tight chambers I'm referring to were actually too tight (diameter) at the body. In some cases they caused cartridges to jam tight against the chamber wall and fail to chamber.
The case width problem is commonly overlooked. Handloaders often find that belted magnum calibers seem to have the most case width problems, but that's caused by a different situation. It's partly due to the limitation of conventional resizing dies when handloading a case with a belt. Just keep in mind that a Go /No-go gauge is only designed to detect headspace (length) problems, and remember that "case width" is also an important consideration.
Go /No-go Gauge
This is what a set of .308 Winchester Go/No-go gauges look like. They are designed to verify that chamber headspace is within the SAAMI spec tolerance from the base of a case to its shoulder. It's best to use them after removing the ejector on most rifles, so that you can "feel" these gauges as they are chambered. These gauges help you verify that any factory loads should fit in your chamber, and be safe to fire.
When reloading, it is important to always bump the shoulder of your cases back at least .001" - .002" to ensure a reliable fit in your chamber. There is no accuracy gained by crushing a cartridge into your chamber. This affects the concentric alignment in a negative way, and it can wear the lugs of your bolt. Keep in mind that most necked cases are tapered, and the wall of your case should never press against the chamber.
Not all chamber reamers are perfect; and as they begin to wear out, they will cut tighter chambers. A set of these Go /No-go gauges will rarely detect the work from a defective or worn chamber reamer. This is because headspace gauges can't check the width of a chamber.
I have examined custom chambers that checked out perfectly fine with Go /No-go gauges, but these chambers had "excessively" tight body diameter. Match chambers are always a bit tighter at the neck and usually require handloaders to do some neck turning, but the rare tight chambers I'm referring to were actually too tight (diameter) at the body. In some cases they caused cartridges to jam tight against the chamber wall and fail to chamber.
The case width problem is commonly overlooked. Handloaders often find that belted magnum calibers seem to have the most case width problems, but that's caused by a different situation. It's partly due to the limitation of conventional resizing dies when handloading a case with a belt. Just keep in mind that a Go /No-go gauge is only designed to detect headspace (length) problems, and remember that "case width" is also an important consideration.
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As posted over on Practical Riflery, a chamber being 'sub-minimum' diameter wouldn't cause a split or separation as you describe. Excessive headspace would, or over-pressure would. I am glad you have the issue fixed (you've fired the rifle since its return and it is, indeed, fixed, right?). Still, I think there were two separate issues at work here. Hopefully, correcting the one will have the impact of 'correcting' the other.
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92 Posts
The case didn't seperate where the normal stretched case does and the go/no go gauges didn't show any problem. The only thing I can think of is the over resizing caused the problem. Yes the rifle is fine now and everything is working as it should.
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