Case head separation

[thatmikeguy]

i have a .308 parker hale and i am experiencing case head separation with fairly new cases. i use the lyman 49th manual so it's not like i'm guessing at how much powder to use. i tried backing off the powder charge and i still see a tell tale ring in the inside but not all the way around. do you know much about this? any tips? is it normal for cases to have a slight ring on the inside throughout their life? i'm just learning about this. never had this issue before.

 

[mikeyb]

How long have you had the gun? Are these the first rounds you've fired out of it? What is the load you're using?

 

[M12shooter]

New brass or range brass? Check the numbers on the bolt handle as to serial number.

 

[purple]

How many firing cycles on the brass, and are you FL resizing each time? Sounds like headspace could be on the long side, so it would be a good idea to have it checked. Even with excessive headspace, you can still manage the problem in a bolt gun by necksizing. FL resizing where headspace is a bit long causes an inordinate degree of brass working and brass flow by firing the case and then compressing it again. This leads to early case separation.

 

[Pathfinder]

How many firing cycles on the brass, and are you FL resizing each time? Sounds like headspace could be on the long side, so it would be a good idea to have it checked. Even with excessive headspace, you can still manage the problem in a bolt gun by necksizing. FL resizing where headspace is a bit long causes an inordinate degree of brass working and brass flow by firing the case and then compressing it again. This leads to early case separation.

Bang on,

You can either neck size or partial resize your fired brass with your FL die by backing off the shell holder a bit .

As mentioned getting it checked by a Gunsmith would be a good idea at this point.

 

[28 gauge]

I had this same problem sometime in the past with one of the .308 rifles I owned.I cured the problem by just resizing the cases till the bolt would just close over the shell head.I had to keep these shells seperate from my other full lenght resized cases as they would not work in all my other .308 rifles.

 

[JasonS]

How many firing cycles on the brass, and are you FL resizing each time? Sounds like headspace could be on the long side, so it would be a good idea to have it checked. Even with excessive headspace, you can still manage the problem in a bolt gun by necksizing. FL resizing where headspace is a bit long causes an inordinate degree of brass working and brass flow by firing the case and then compressing it again. This leads to early case separation.

I agree too. Full length sizing in the past with a 7mm RemMag I got 3 firings only before tossing them out. I use the LEE Collet sizer for all calibers now. Brass lasts longer and super accurate loads with the fireformed brass. Best $20-25 you can spend.

 

[thatmikeguy]

i use a lee collet die for neck sizing. i bought the gun last year and for quite some time i used 165gr bullets with 42 grains of imr4895. when i bought my manual it said i could use 43.5 grains for the 165's and 175's. i started having problems with the 175 grainers and the new load and that particular time i FL sized. since then and before i neck size only. those cases at that time were well used so i just threw them out. i am currently using once fired cases and would like to solve this issue before opening my new bag of brass. my last test was with 175 grainers in once fired brass with 41 grains of the same powder. the cases have a partial strech line on the inside and nothing on the outside. the primer still has a rounded edge. when i fired 165's with 42 grains of powder i never had this problem but i was also not aware of case head separation at the time so i never looked inside the case but i never had one split then either.

 

[JasonS]

Now it sounds like you need to get the headspace checked and go from there. But one thing, are you sure you are seing a stretch line and not the chamber endline? Take a paperclip, straighten it out. sharpen one end to a point and bend that end so it's 90 degrees at about 1/8" from the pointed end. Use that bent point to feel the inner wall of the cases all the way down. If they are really stretching you will feel a groove with that little point.

 

[thatmikeguy]

i'll try it. it looks like a stretch line...

 

[rembolt]

Don't mean to hijack but is there a reason this seems to happen from the inside of the case.it will appear as a shiney ring on the outside but if you do as discribed with the paper clip you can actualy feel the crack.

 

[thatmikeguy]

sometimes there is a shiney ring. i've seen it. but it seems to start on the inside. only a few have actually split. when i see the ring on the outside i trash them.

 

[struff55]

Its a resizing issue not a head space issue just partially re size your brass and you will be fine there is no need to full length size in a bolt gun .

 

[Baribal]

The reason why this happens is excessive stretch, either from reforming too short or excessive headspace. The more common is definitely excessive REFORMING.

The case stretches and the base (head) of the case is the hardest place (work hardened), so, for that reason, the material will extend less (Yield point). It happens from the inside mostly because most of the work hardening is made there and that's also where to pressure is applied.

as an example, this case was reformed too short;

 

[rembolt]

The reason why this happens is excessive stretch, either from reforming too short or excessive headspace. The more common is definitely excessive REFORMING.

The case stretches and the base (head) of the case is the hardest place (work hardened), so, for that reason, the material will extend less (Yield point). It happens from the inside mostly because most of the work hardening is made there and that's also where to pressure is applied.

as an example, this case was reformed too short;

Thank you a very good explanation

 

[smellie]

Excuse me, guys, but there could be a reason behind all this.

Parker-Hale did not always serial the bolts to the rifles. They only started after what happened in Canada. One of the really big mail-order houses brought in a whole WHACK of brand-new Parker-Hale rifles and sold them at a discount. That was fine. But they didn't want to mess about with them too much (costs money) so they hired a bunch of college students for the summer to clean the things up, degrease them and so forth. The kids knew nothing at all about guns....... so they tossed all the bolts into tubs and washed the grease out of them and slapped them back into rifles.

Problem was that they didn't know diddly-squat about what they were doing. Some rifles got bolts that worked fine, PH generally being pretty careful and uniform about what they do, but some rifles ended up with bolts with not enough headspace.... which ended up at gunsmiths' shops, of course.

And some rifles ended up with bolts giving too much headspace.

In parts of Alberta, where a lot of these rifles were sold, you can barely even give away a PH to this day. I worked in a gun-shop in Wainwright and if you even suggested a PH rifle, people would laugh because "everybody knows" that they are garbage.

Well, they aren't garbage, by any means. They are darned decent rifles. I just can't afford one.

The cure to this gentleman's problem (excess headspace in his rifle) is to get some fired brass from ANOTHER rifle which doesn't have the problem, then CAREFULLY neck-size this brass ONLY, THEN try it in his rifle. It will stretch lengthways, sure, but it won't stretch as MUCH, reducing the problem to more-or-less manageable proportions.

The IDEAL solution would be to get some of that .308-size basic brass and size it down just enough for this rifle, then shoot it with the ammo which fits this rifle. But that brass doesn't seem to be available and nobody sells semi-finished brass, it seems.

Another way to do the same thing would be to open out new .308W brass to handle an 8mm slug, THEN neck-size it back down to a .308 in STAGES. When it gently contacts the front of the chamber, you should FEEL it stop. That's far enough; you now have a sort-of-a secondary shoulder on the stuff. You load it with a mild load and shoot it. Afterwards, the shoulder should blow forward and you now have brass that FITS.

Good luck!

 

[rollie100]

[youtube]YE0A5IsR1dA[/youtube]

not sure if you wanted a technique of finding head separation or not, but here yah go anyway...

also a shiny ring at the head may also be from sizing and not head separation, good reason to check every case after a few loadings...

 

[rookie wildcat]

Excuse me, guys, but there could be a reason behind all this.

Parker-Hale did not always serial the bolts to the rifles. They only started after what happened in Canada. One of the really big mail-order houses brought in a whole WHACK of brand-new Parker-Hale rifles and sold them at a discount. That was fine. But they didn't want to mess about with them too much (costs money) so they hired a bunch of college students for the summer to clean the things up, degrease them and so forth. The kids knew nothing at all about guns....... so they tossed all the bolts into tubs and washed the grease out of them and slapped them back into rifles.

Problem was that they didn't know diddly-squat about what they were doing. Some rifles got bolts that worked fine, PH generally being pretty careful and uniform about what they do, but some rifles ended up with bolts with not enough headspace.... which ended up at gunsmiths' shops, of course.

And some rifles ended up with bolts giving too much headspace.

In parts of Alberta, where a lot of these rifles were sold, you can barely even give away a PH to this day. I worked in a gun-shop in Wainwright and if you even suggested a PH rifle, people would laugh because "everybody knows" that they are garbage.

Well, they aren't garbage, by any means. They are darned decent rifles. I just can't afford one.

The cure to this gentleman's problem (excess headspace in his rifle) is to get some fired brass from ANOTHER rifle which doesn't have the problem, then CAREFULLY neck-size this brass ONLY, THEN try it in his rifle. It will stretch lengthways, sure, but it won't stretch as MUCH, reducing the problem to more-or-less manageable proportions.

The IDEAL solution would be to get some of that .308-size basic brass and size it down just enough for this rifle, then shoot it with the ammo which fits this rifle. But that brass doesn't seem to be available and nobody sells semi-finished brass, it seems.

Another way to do the same thing would be to open out new .308W brass to handle an 8mm slug, THEN neck-size it back down to a .308 in STAGES. When it gently contacts the front of the chamber, you should FEEL it stop. That's far enough; you now have a sort-of-a secondary shoulder on the stuff. You load it with a mild load and shoot it. Afterwards, the shoulder should blow forward and you now have brass that FITS.

Good luck!

Hey,that was gonna be my idea!! I have fixed this problem on a couple of rifles just by segregating the brass fired in it. I sized it only enough so that it would chamber. Loaded a squib load of 5 or 6 grains of Unique, fired it and then only neck sized making sure that that brass was only for that gun. I have since taken to keeping all my brass separated by firearm since I now neck size only.

 

[kombayotch]

Its not hard to make a tool that probes for it. I used to just put the probe in a vice and mount the dial indicator on the vice before I made this adapter. You just drag the case between the probe and indicator. What you expect to see is the case wall getting thicker towards the base. The needle should move smoothly. If it jumps, there is a gap starting to form and you can go back and measure its depth. This is way faster and more reliable than feeling with a paperclip.