The cartridge case above is a 270Win. It was fired from a Winchester M70. I purchased the rifle new in 1990 and have shot several hundred rounds through it. The brass is about the same vintage as the rifle, and has been reloaded several times. Some of the loads were fairly hot, but none exceeded the recommended max for that powder and bullet. This particular reload held 58.5gr H4831 behind a 130gr Hornady SST. I have gone up to 59.5 gr with sticky extraction and backed off a grain. In the same group of six rounds, one other case separated like this one.

I don't think the problem lies with the rifle, as this has never happened before in the 16 years I have had the gun. I tend to suspect faulty reloading techniques combined with worn brass.

Does anyone have any ideas as to why this may have happened?

That is what happens to old brass, especialy if they have been full length resized a number of times.
Lyle

It was more than likely caused by overzealous full length resizing. That is to say, the case shoulder was pushed back too far on resizing. Upon firing, the case grew in length at that part of the case body, thinning it over a few squeezing and then lengthening cycles. I have seen pictures of separations and incipient separations in every one of my reloading books. Not yours?

Dear Wooly Ess:

I had an identical head separation with a 243 Winchester case years ago. Probably, I full length resized it one too many times. I agree with the other people here that your full length reloading die could be set too close to the ram, and your shoulder is pushed back to minimum specifications. If you have a maximum spec. chamber and head space, and a minimum spec. case, well that's it, a separated case.

On the other hand, why don't you have a gunsmith check the headspace to eliminate that other possibility. If you know your headspace is okay, then its the full length sizing issue, but if the headspace is not okay, well, then your next step is up to you.

I pretty much neck size all my cases approximately 3/4ths of the way down the neck. Sometimes after 7-8 loadings, I have to just tap the shoulder back a bit on my 7x57 AI with a full length sizing die.

Sincerely,

Chris Bemis

You should re-size cases so that they are a slight crush fit, or when you close the bolt there is a little resistence, you can usually see a bright ring on the shoulder. You can decrease case re-sizing by backing the die out or away from the ram this will partially resize as opposed to fully re-sizing the case.

Buy a set of stoney point gauges and use them to set up your dies. It looks like you have been full length resizing the brass. What you need to do is resize it just enough to push the shoulder back a thousand or two. It's real easy to see how much you're setting back the shoulder by using these gizmos attached to your calipers, then you just adjust your die for the proper shoulder setback. Doing this you will greatly extend the life of your brass. I'd throw all of that old brass away and get some new. Getting cases out of a chamber with the head torn off isn't fun, I've been there.

If you've been shooting that rifle for 16 years, I'll not be telling you anything you don't already know about sizing, etc., so won't use the bandwidth.

Will just remind you, though, that the reason brass is commonly used for cartridge cases is that it easily stretches to fill the chamber and seal off gas flow too. Stretching every time it fires both hardens and embrittles the brass.

Being brass, it is basically a throw-away item and is not intended to last the life of the rifle. Properly treated by the handloader it will usually last 5-10 reloadings, sometimes less, sometimes more, depending on load and rifle. But it still has a finite, relatively short life.

In the "old days" with cartridge cases like the .270, .30-06, and others of similar or higher intensity, most of the better "hunting writers" reminded folks to use their brass only at the range if it had been reloaded more than two or three times, Aand NOT to take it hunting. For hunting they recommended either new brass or brass which had been fire-formed and then loaded not more than a couple more times.

What you have in hand is exactly why they used to say that. They probably should still make a point of it.

Best wishes, and good shooting...

AC

The loads you are using are great loads,no problem with that. Your brass just got tired! This does happen and its no big deal.This is the week spot in brass from full lenght resizing. You might have this happen again in that older brass you have. Some guys watch out after there brass and keep it seperated from others in respect to how many times it has been reloaded. van

Yep, like the others said, that's what happens once you load the brass a few times. The hotter the loads the sooner you'll see the expansion ring. I bet the brass probably showed this ring before you fired them.

PFL resizing will help your brass life but hot loads will still shorten brass life.

Good Luck

Reloader

With a full seperation such as you show I believe that is from overworking the brass in a improperly set up resizing die.

When a shot is fired, the case expands outward to tightly grip the walls of the chamber, but the solid web portion does not noticeably expand under a safe pressure load which results in the fired case having a somewhat larger diameter just forward of the web. It follows that 'tight chambers' will allow less case expansion than 'loose chambers', and hence case life will vary. The stretch happens where the relatively thick case wall starts to taper forward into the thinner body portion of the case. When a case is run fully into a conventional full-length sizing die, the exterior case dimensions are pushed back to minimum specifications so that the round will chamber in any make of rifle. Each subsequent firing and sizing of the case increasingly work-hardens that section of the brass that stretches. Eventually, after so many successive firings and full-length sizings, the case will separate (fail) just forward of the web - this we call 'case head separation'. That is why neck-sized cases last longer than full-sized cases. For long case life, the case should not be sized no more than necessary to chamber smoothly and the shoulder of the case should not be set back any more than necessary - none, if possible.

Case head seperation happens with both 'standard' (beltless) and belted cases, but watch in particular those cartridges that headspace on the belt, like the 7 mm Rem Mag, 300 Win Mag, 338 Win Mag, 300 H&H, 375 H&H, 416 Rem Mag, the 458 Win, as some brands of cases have sloppy belt tolerances giving rise to headspace problems. In addition, those cartridge cases that taper towards the front as opposed to those that run parallel, are also more prone to stretching as they get gripped less firmly by the chamber walls. We need to bear in mind the design criteria for tapered cases. Tapered cases were actually designed for dangerous game hunting in hot climates, such as Africa and India, to ensure reliable extraction to avoid stuck cases in the chamber when you are in dire need to fire a second shot. Furthermore, 'hot loads' naturally yield higher pressures which in turn exacerbate brass flow.

Warrior

A case head seperation from time to time is part of the cost of doing business as stated above. Normal non maximum loads may become over max if attention to detail, as in neglecting to trim cases occasionally, etc.

How long do you expect brass to live?

Wooly, you need to change your underwear, and brass at least every decade.

Case life does not only vary per brand of cases, but also for differnt cartridges as the case design varies - ie long sloping taper of body and shoulder (easier to flow) vs cases with more parralel sides and a sharper shoulder. In also depends on chamber dimentions (loose or tight). The cases of high-pressure cartridges naturally get "abused" more than low-pressure cartridges - eg 7x57 mm vs 270 Win.

Generally in hunting rifles with standard factory chambers I would say 10 times when no abuse is present. Reloading manuals suggest neck annealing for the fifth firing to avoid neck cracking. Some brass, like PMP and Lapua, are thicker than others, such as Winchester and Norma, and are generally tougher. I have used my PMP cases 7 times now without annealing and I retired them now as the annealing is a slept for me. Do inspect your cases every time - in fact reloaders have the habit of doing it soon after the shot has been fired - looking at any funny marks, indentations, primer condition, sealing of the neck to see where the blow-back stopped, if insipient cracks are developing just forward of the webb, etc.

Benchrest shooters that use rifles with tight chambers can get between 50 and 150 firings depending on the individual cartridge and load. This then gives us an idea what role the chamber plays in case life.

Aslo beware of doughnut forming in the 243 Win and 270 Win, as brass flow seems to happen more readily with these two calibers, as they have long sloping shoulders that are prone to brass flow and an internal ridge forms just at the start of the neck. Always slip a bullet through before reloading again, making sure the bullet would not get pinched when seated. Doughnuts causes pressure spikes and could be dangerous.

Warrior

Warrior,
You have a PM.

Thanks Gerard.
I have contacted Nick.
I have a box of your .366/230gr HV's
Would love to try them on game this season.
Having seen the 260 gr retrieved bullet from Nols, I am sure they are going to work great for the longer distances out in the open plains.

Have a lovely easter weekend.
Chris

Thanks for all the helpful and informative replies. I plan to do three things:

1. Throw out ALL my existing 270 brass.

2. Back my seating die out of the press a small amount.

3. I may also try a neck sizing die.

I recently had a similar case head separation in a 338 win mag and Norma brass. As best as I can determine the cases had been fired about 6 times. The load I was using was perhaps a little stiff but the primer pockets were still tight.

The brass had been neck sized for the first three loadings and partial full length resized with the shoulder being pushed back .001" after that. It was a batch of 20 and the separation took place on the 2nd firing at the range in a Beretta Mato which has a Lothar Walther barrel. I did not fire the rest and pulled the bullets on the remainder and looked for a groove on the inside with a bent paper clip. I could not find evidence of any abnormality on the other cases.

Of course, I trashed the rest of the brass and will start over. How come Lapua or Nosler don't make 338 win mag brass?

I always thought that when the firing pin slammed the brass forward, the brass expanded and gripped the chamber walls and the brass pushed back to the bolt face expanding at the place where it was not binding on the walls of the chamber. That would be in the pressure ring area where these case head separations occur.

Neck sizing also has the advantage of not sizing the case body allowing an instant bind on the chamber walls. But after a couple of firings the shoulder has to be pushed back in order to prevent a crush fit binding when chambering. Is there a way to resize the neck and push the shoulder back without sizing the case body?

Warrior, you mentioned the doughnut. Is there a way to get rid of it other than the K & M neck turner mandrel with the cutter head? I know that if you neck turn and cut a little into the shoulder that it is supposed to mitigate doughnuts.

quote:

Warrior, you mentioned the doughnut. Is there a way to get rid of it other than the K & M neck turner mandrel with the cutter head? I know that if you neck turn and cut a little into the shoulder that it is supposed to mitigate doughnuts.

Woods,

The neck turn does help a little. Sloppy factory chambers, especially the portion where the case neck fits adds its portion of the problem and that is a frustrating factor. I think the 243 is one of those cartridges that really call for more precise and tighter tolerances to negate the doughnut effect.

Years ago (mid 70's) PMP had the problem with .243 Win cases splitting their necks on the first firing, and as a result they had a lot of ammo withdrawn once it became known.

I must say though that I have seen a few .243 Win made by Ruger that have been behaving very well and can only surmise that they had well cut chambers.

Warrior

Woods,

I have never done inside case-neck turning myself, as I do not have the tool for it. K&M has a tool for this operation and you can read more about cutting the ridge inside the case neck - just visit mywebpages.comcast.net/jesse99/doughnuts.html

Warrior

Woods,

The article that I refered to seems like hard work and is not conducive to motivating people to get embroiled with cutting doughnuts away - most will follow the path of least resistance and simply use brand new cases again.

Warrior

I'd love to know if this gun has had a headspace check.....I'll bet it has excess headspace.

quote:

Originally posted by vapodog:
I'd love to know if this gun has had a headspace check.....I'll bet it has excess headspace.

Hey vapo

The dreaded "excess headspace", let's talk about that. I had a pre-64 model 70 in 264 that a new WW case measured 4.109" with a Head & Shoulders Gauge. The first firing took it to 4.136" and 2 of the cases burned through at the shoulder. That was excessive headspace.

But, it was only excessive headspace on new cases, after that the cases were fireformed and close enough to chamber dimensions that there was no longer excessive headspace. Perhaps in that first firing the case was thinned too much at the pressure ring and the cases would have been more prone to casehead separation.

But, was it the fault of the chamber or that sorrya$$ WW brass being undersize? As near as I can measure the WW brass was about .015" shorter to the shoulder/neck junction and to the case body/shoulder junction than what is listed in the Nosler #5 manual. I had not started measuring the shoulder when I first loaded the 338 win mag where I had a case head separation so I don't know if the new brass was excessively small or not.

I suspect that if you are loading hot, that any headspace is excessive and will cause thinning at the pressure ring. Therefore, Partial Full Length Resizing and minimal headspace created during sizing is more important than ever.

READ what onefunzr2 said that's your problem.

It's not your seating die that you need to back out it's your sizing die.

Brass does not go to shit by just sitting or reloading 2 times.

Sorry, my bad - I meant sizing die.

Excessive headspace or excessive cartridge headspace will cause case head separations. I have a set of rifle headspace gages, and I use the 30-06 ones to check the 270 rifles. If the rifle accepts the “go†but not the “no go†then the rifle is mechanically correct.

I also use a cartridge headspace gage. I full length resize cases to gage minimum. The cartridges can now be fired until the primer pockets open up or the case necks split which for me, this is around 20 full power reloads. I have never had a case head separation with when I have properly set up my sizing dies.

This is all a matter of controlling your mechanical tolerances. I tried setting up sizing dies without case gages, following similar advice postings, and I can tell you it is all well intentioned bunk. Once you have the ability to measure what you are doing, you will find out that all your previous practices were “bubble, bubble, toil and trouble, eye of newt, toe of frogâ€.

For a hunting rifle where function is paramount, I would never recommend neck sizing. One day you will find that you cannot close the bolt on a neck sized round. You will be beating the back end of your bolt handle and either the opportunity will eat you, or it will run away.

I highly recommend going to this sight and viewing the pictures on using a cartridge headspace gage.

. http://www.realguns.com/Commentary/comar46.htm

quote:

Originally posted by SlamFire:
I tried setting up sizing dies without case gages, following similar advice postings, and I can tell you it is all well intentioned bunk.

Slamfire

I don't recall anybody giving advice above to set up sizing dies without a case gauge. Are you referring the above posts as well intentioned bunk?

quote:

Once you have the ability to measure what you are doing, you will find out that all your previous practices were “bubble, bubble, toil and trouble, eye of newt, toe of frogâ€.

It sounds like you are saying that if you don't measure headspace the way you do then all else is witchcraft.

quote:

For a hunting rifle where function is paramount, I would never recommend neck sizing. One day you will find that you cannot close the bolt on a neck sized round. You will be beating the back end of your bolt handle and either the opportunity will eat you, or it will run away.

Do you think that if you can neck size a case and have it still chamber easily that it is more likely to cause a field problem than a Full Length sized case? In what way? I neck size until I start to get a crush fit then regulate exactly how much with a body die.

I have a Wilson Gauge somewhere in the back of my drawer. After I got the Stoney Point Head & Shoulders Gauge it saw no more use. It worked but not nearly as easy and did not provide as much information about what was going on.

Like the saying goes, "There's more than one way to skin a cat". You shouldn't degrade other methods until you've tried them.