Thread: Case head separation imminent

My suggestion is that the cases may not be as alike as you think. The manufacturer may be the same but unless you bought the whole 200 at the same time and of the same batch there could be some significant differences in case body brass hardness and structure. You could just be seeing the weaker cases failing first. This is exactly what you would expect. Check the inside of the surviving cases with a bent paper clip with the end bent and sharpened to a point to see if there is a groove is developing. You have not told us how you set your sizing die to eliminate excess head space. Ask any questions you may have, between us we all may learn something.
Regards Grandpamac.

Originally Posted by Moa Hunter

Could you put up some pictures of the marked cases before and after please

I'll work on that - reloading gear is a bit of a mess at the mo as I'm in the process of relocating it...

Padox, was the first firing as factory ammo in the same rifle as the next one or two firings?

I’ve had case separations after two firings in my .30/06. First firing in a different rifle to the second. Both same make but obviously dimensions in the chamber and brass flowed forward.

Also had a couple in my .35 w as a result of pushing the shoulder back a bit to far when sizing .30/06 brass up for the first firing.

In a R700 the gas vents through the hole in the receiver and some via the magazine. Not a issue if hand is away from the area.



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Yes I brought 120 rounds of hormandy superformance ran them then started reloading with them

Originally Posted by Padox

Yes I brought 120 rounds of hormandy superformance ran them then started reloading with them

How do you set up your dies?
I'm picking your rifle might have a chamber at the big end of Saami spec and FL dies set up to instructions will cause this fairly quickly.

As per instructions on dies

I was given some ( 100 ish ) once fired factory cases - 270 Rem Corelokt that had been fired in an Xbolt. Those cases appeared to have a slight blown forward bulge between the shoulder and the start of the neck. They would not chamber in any of the three 270's I have. I used them for loads in the re-barreled BSA hunter with the overlength chamber and they wouldn't even chamber in that rifle without a shoulder bump. How much longer than Sammi spec that XBolt chamber was I can only guess

Originally Posted by Padox

As per instructions on dies

Greetings @Padox,
Congratulations you have identified the problem. My son lent me some Hornady headspace comparators and some sets of the Redding competition shell holders earlier this year. I had long been in favour of neck sizing but he had been using the above kit for his target rifles. An extensive measuring session followed. This was a revelation. Only one of my rifles had a chamber that gave the desired 0.05 mm (0.002") shoulder bump when sized with the standard shell holder. With others the bump ranged from 0.1mm (0.006") to an outlier of 0.3mm (0.012'). The comparator clamps onto the jaws of your calliper which I assume you have and are not over expensive and before and after sizing measurements will tell you how much you are setting the shoulders back when sizing. You can then either purchase the shell holder kit (which are more expensive) or adjust your die by trial and error to get the desired shoulder bump. Once done your head separations will cease.
Regards and all the best Grandpamac.

Originally Posted by grandpamac

Greetings @Padox,
Congratulations you have identified the problem. My son lent me some Hornady headspace comparators and some sets of the Redding competition shell holders earlier this year. I had long been in favour of neck sizing but he had been using the above kit for his target rifles. An extensive measuring session followed. This was a revelation. Only one of my rifles had a chamber that gave the desired 0.05 mm (0.002") shoulder bump when sized with the standard shell holder. With others the bump ranged from 0.1mm (0.006") to an outlier of 0.3mm (0.012'). The comparator clamps onto the jaws of your calliper which I assume you have and are not over expensive and before and after sizing measurements will tell you how much you are setting the shoulders back when sizing. You can then either purchase the shell holder kit (which are more expensive) or adjust your die by trial and error to get the desired shoulder bump. Once done your head separations will cease.
Regards and all the best Grandpamac.

So you are suggesting that it is actually variation in shell holders that are giving us trouble with reloads just as much as anything else ?

It's just odd that iv never in the 10yrs iv been loading for it had an issue bfor now

Originally Posted by Padox

It's just odd that iv never in the 10yrs iv been loading for it had an issue bfor now

It is odd, but at least this thread came up at the right time to help

Originally Posted by Moa Hunter

So you are suggesting that it is actually variation in shell holders that are giving us trouble with reloads just as much as anything else ?

Greetings @Moa Hunter and all,
No the shell holders are generally pretty good. The problem is with the tolerances between the chambers and dies. The maximum case needs to fit in the minimum chamber so there is a tolerance between those sizes (the maximum size case has a shorter headspace dimension than the shortest chamber. Additional to this there is a tolerance in both the dimensions the case and the chamber so a minimum case can be quite loose in a maximum chamber. This is the problem that I think @Padox is having. This afternoon when it is too hot for putting firewood away I will try and put some figures on this. For belted cases and some cartridges not originating in the US the problem can be much worse.
Regards Grandpamac.

Greetings all,
I currently have two sets of .223 Rem sizing dies here so I thought it might be useful to compare their sized cases. I selected two once fired cases that had been fired in my old Brno. Each was de capped with a punch and base set and one sized in each die with the decapping stem removed to eliminate one more variable. The case were then measured in the comparator and the RCBS die set the shoulder back an additional 0.04mm (a bit less than 0.002") which is actually quite close. With the RCBS dies I would need the +0.002 shell holder rather than the standard one
Next I hunted out a copy of the SAAMI chamber and case dimensions for the .270. The maximum case would be a slight crush fit in the minimum chamber which would be hard to notice in chambering but the minimum case would be a very loose fit in a maximum chamber at 0.333mm clearance (about 0.013"). This is enormous. The headspace dimensions for the .270 were taken from the .30-03, a forerunner of the .30-06. Later cartridges may have tighter tolerances but this reinforces the point that setting the die down hard on the shell holder is going to result in early case head separations in many rifles.
Regards Grandpamac.
Some cases are much more stoutly constructed and so may take longer to separate but separate they will in time if they are oversized.

Originally Posted by Padox

As per instructions on dies

Originally Posted by grandpamac

Greetings all,
I currently have two sets of .223 Rem sizing dies here so I thought it might be useful to compare their sized cases. I selected two once fired cases that had been fired in my old Brno. Each was de capped with a punch and base set and one sized in each die with the decapping stem removed to eliminate one more variable. The case were then measured in the comparator and the RCBS die set the shoulder back an additional 0.04mm (a bit less than 0.002") which is actually quite close. With the RCBS dies I would need the +0.002 shell holder rather than the standard one
Next I hunted out a copy of the SAAMI chamber and case dimensions for the .270. The maximum case would be a slight crush fit in the minimum chamber which would be hard to notice in chambering but the minimum case would be a very loose fit in a maximum chamber at 0.333mm clearance (about 0.013"). This is enormous. The headspace dimensions for the .270 were taken from the .30-03, a forerunner of the .30-06. Later cartridges may have tighter tolerances but this reinforces the point that setting the die down hard on the shell holder is going to result in early case head separations in many rifles.
Regards Grandpamac.
Some cases are much more stoutly constructed and so may take longer to separate but separate they will in time if they are oversized.

Grandpa Mac has well covered ( perhaps more easily understood hopefully)again what I was trying to explain in post 1 and 2.

If your rifle has large chamber dimensions and you shoot factory ammo then it's going to stretch a lot on the first shot no getting around that....but when you reload those cases if you set up your dies correctly instead of following the instructions your brass life will be much better.

Originally Posted by grandpamac

Greetings all,
I currently have two sets of .223 Rem sizing dies here so I thought it might be useful to compare their sized cases. I selected two once fired cases that had been fired in my old Brno. Each was de capped with a punch and base set and one sized in each die with the decapping stem removed to eliminate one more variable. The case were then measured in the comparator and the RCBS die set the shoulder back an additional 0.04mm (a bit less than 0.002") which is actually quite close. With the RCBS dies I would need the +0.002 shell holder rather than the standard one
Next I hunted out a copy of the SAAMI chamber and case dimensions for the .270. The maximum case would be a slight crush fit in the minimum chamber which would be hard to notice in chambering but the minimum case would be a very loose fit in a maximum chamber at 0.333mm clearance (about 0.013"). This is enormous. The headspace dimensions for the .270 were taken from the .30-03, a forerunner of the .30-06. Later cartridges may have tighter tolerances but this reinforces the point that setting the die down hard on the shell holder is going to result in early case head separations in many rifles.
Regards Grandpamac.
Some cases are much more stoutly constructed and so may take longer to separate but separate they will in time if they are oversized.

That bit about the origin of headspace dimensions for 270 is very interesting - and the wide variation possible, esp considering it is a 65000psi max case. Certainly the Xbolt fired cases I was given were way long. I didnt worry about that too much figuring they could handle one stretch / fireform from new ( hope I was right), they were then sized to just chamber nicely in the old BSA Hunter and loaded with a light load ( start load of 2217 for 2660 fps 130 partition) to mimic a light 7x57 load.