Thread: Case head separation imminent

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

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.

Originally Posted by Moa Hunter

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.

Hmmm,
Light load in a .270 BSA Hunter to mimic a light 7x57 load? Perhaps a 7x57 barrel is not far away?
GPM.

Originally Posted by grandpamac

Hmmm,
Light load in a .270 BSA Hunter to mimic a light 7x57 load? Perhaps a 7x57 barrel is not far away?
GPM.

Would be nice but hey thats the barrel its got. I mentioned in an earlier post that it had been a 7x57, then re-barreled to 270 (with a fluted Weatherby barrel) before I was given it. The action is way less strong than the Rem 700 so light loads seemed sensible, that combined with it being a very light rifle

Padox,
If it was me in your situation, I would back my FLS die out from where presently set gradually until I could just feel the case on the bolt close and load a few there.

52 gns of 760 is a light load for 130s. Are your shooting 150s?

ww760 is a great and underrated powder in the .270Win.


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Where its set u can just feel them the odd 1 even a little tight am running 130s 53.5 is max book for 760

Originally Posted by Padox

Where its set u can just feel them the odd 1 even a little tight am running 130s 53.5 is max book for 760

Are the cases all previously fired in the same rifle? Normally a fired case will chamber back in the same rifle easily and get tight if it has been neck sized alone for several firings, then needing a full length resize. The recommended best practice now is to set the shoulder back a tiny bit at each reloading rather than wait for the case to grow too much. Have you trimmed the necks of the cases ? If the tip of the neck is a crush fit where the chamber - throat steps into the barrel that can make the reloader (me) think the shoulder is still tight and screw the die down a bit more

Greetings @Padox,
There is quite a bit going on in the last bit of bolt closure in a Remington 700. One of these is the extractor being forced over the rim of the case. This can be read as a tight case when the case is still loose in the chamber. Generally a tight case will also show a rub mark (shiny patch) on the base usually on the outer edge. I have 3 Remington 700 rifles and this is what I have found with some. For this reason I would recommend the Hornady comparator so you can work to a measurement rather than feel. If you ask around locally you might be able to find someone who has one. Trimming cases to the correct length as @Moa Hunter suggests above is also essential.
Regards Grandpamac,

Padox,
55 gns with a 130 for 3000 fps is pretty common in a lot of .270s. You rifle and cartridge components may be giving you this performance perhaps. Guess what I’m saying is your load is likely not an issue in the discussion.


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What a timely post to come back home to after a hunting trip at the weekend!


Have reloaded for years without to many issues but at the weekend i fired a shot and extracted the head of the cartridge only.
The rest was jammed in the chamber, which was not a happy time with a bunch of tahr standing there looking at us and no functioning rifle!
Trudged a long way back to the hut and managed to pull the stuck case with a pull through.

Back up the hill and fired two more shots and was horrified to find cracks in the next two also.

The brass has only been fired two times, no head space issue in the rifle, load rechecked on the scales and dies set as per instructions also.

Ok, so from reading through the rest of this post , it seems the dies are also not set up properly and will be oversizing the case causing a headspace problem that is allowing the case to much expansion when firing??
The dies will be pushing the shoulder down to much?

Does this also mean all my resized brass will be ruined?

Rifle is a 7mm rem mag

Never had the issues before

Originally Posted by yogi

What a timely post to come back home to after a hunting trip at the weekend!
Attachment 209760

Have reloaded for years without to many issues but at the weekend i fired a shot and extracted the head of the cartridge only.
The rest was jammed in the chamber, which was not a happy time with a bunch of tahr standing there looking at us and no functioning rifle!
Trudged a long way back to the hut and managed to pull the stuck case with a pull through.

Back up the hill and fired two more shots and was horrified to find cracks in the next two also.

The brass has only been fired two times, no head space issue in the rifle, load rechecked on the scales and dies set as per instructions also.

Ok, so from reading through the rest of this post , it seems the dies are also not set up properly and will be oversizing the case causing a headspace problem that is allowing the case to much expansion when firing??
The dies will be pushing the shoulder down to much?

Does this also mean all my resized brass will be ruined?

Rifle is a 7mm rem mag

Never had the issues before

Greetings,
Maybe. You can check with a bent paper clip feeling for a groove on the inside of the case. If you feel a groove bin it. Sizing belted cases is fraught with problems. You could (and should) back out the die so it moves the shoulder back about 0.002" but this can allow another problem. A bulge can develop right in front of the belt which makes the case chamber hard. There is a kit to remove the bulge or you can use a stripped 300 Win Mag die to do this. PM me if you want more on this.
The belt on the 7mm Rem Mag is a fashion accessory and serves no useful purpose. There is excess headspace in your rifle but probably within manufacturing tolerances and setting the sizing die down hard on the shell holder as per instructions can result in head separations in many rifles for belted cases. Case construction can be a factor.
Regards Grandpamac.

Good reply above from Grandpamac.

Check the rest of your cases, if they are relatively clean on the outside you can usually see the line but definitely would be worth checking them all with a probe of some sort.

Actually measuring shoulder bump is the best way to control and minimize the stretching in this area but not all of it is headspace caused.
Large chamber dimensions also increase the amount of stretching in this area, for this reason I neck size only my 303 brass and only full length if nessacary and only enough to chamber freely again.

Originally Posted by veitnamcam

Good reply above from Grandpamac.

Check the rest of your cases, if they are relatively clean on the outside you can usually see the line but definitely would be worth checking them all with a probe of some sort.

Actually measuring shoulder bump is the best way to control and minimize the stretching in this area but not all of it is headspace caused.
Large chamber dimensions also increase the amount of stretching in this area, for this reason I neck size only my 303 brass and only full length if nessacary and only enough to chamber freely again.

Greetings All,
Totally agree with measuring shoulder bump especially on belted cases. Setting back the shoulder by feel on a belted case can result in the shoulder being set too far back if there is a bulge in front of the belt. You will feel the bulge as a tight case and keep on setting the shoulder back too far. Measurement is essential to stop this. The bulge needs to be removed.
Regards Grandpamac.