Case head failure gives me something to think about!

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Elkins45

New member
I had a case head failure in my Savage 270 bolt action rifle Monday at the range. The load was 56.0 grains of IMR 4831 behind a Hornady 130 grain spire point. It's the same load I have hunted with for 20 years now. I knew something bad had happened the minute I pulled the trigger because there was smoke everywhere, my face was peppered with powder and I could feel the impact of a jet of gas (and could see a black mark) on my right hand. Fortunately I wasn't hurt in any way, although if I hadn't been wearing glasses I'm pretty confident I would have suffered at least some damage to my vision.

The rifle didn't suffer much damage other than to the extractor, which was blown to the outside of the bolt. It didn't pull the damaged case and I removed the bolt and noticed it had been dislodged. I shoved it back into the correct spot and it seems to be working just fine. It was clear that a LOT of gas had been blasted out of the vent hole on the side of the action from the scorch mark on the stock, the amount of smoke, and the displacement of stuff on the bench next to me. Fortunately I was alone on the line so nobody was next to me to absorb the blast. I'm 99% sure the reason for the case failure was my own stupidity in using an old case one too many times without checking to see if the sidewalls were thinning.

So what's the lesson, you ask? Well, it's this: notice how I described the burn on my RIGHT hand? Well, that's because I'm a lefty. My right hand was the one on the forearm when the rifle was fired---and did I happen to mention that my rifle is a Savage 110L? I was firing a LEFT HANDED rifle when this happened. My support hand was on the opposite side from the vent hole and still managed to get somewhat burned. So there's the lesson: imagine if it had been a right handed gun and my hand had been beside the vent hole! I'm not at all sure I wouldn't have suffered significant damage to my off hand. Owning a left handed rifle has been a relatively recent indulgence for me since I've reached middle age. I've done (and still do) most of my shooting with right handed bolt guns. In many cases they are the only ones available. If you want to shoot 98 Mausers, for instance, or 1903 Springfields then you'll be shooting RH guns. I wonder if maybe that's not such a good idea.

I know case failures are somewhat rare, but maybe once is enough. So here are all the lessons I learned:

1) Glasses, prescription or otherwise, should be on your face EVERY TIME you pull a trigger. I'm confident they spared my vision to some degree.

2) Check cases for impending head separation if they've been used more than a couple of times.

3) Maybe buying dedicated LH guns is less of an indulgence and more of a wise precaution. I'm certainly thankful this round failed when I was shooting a gun designed to vent gasses away from my hand rather than toward it.

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How many times was that brass loaded?

With commercial brass, I usually get 10+ reloads out of my .308's and 30-06's before I start getting the "ring", thats assuming the case mouths last that long.

I usually start checking with my homemade paper clip "tool" at around load #7.

Headspace can also be an issue here. I had an Ishpore SMLE in .308 that was having separations after the first reload.
 
Looking at that case it shows signs of being over pressure. Along the rim at the top right you can see where the brass has a pretty good impression on it from excessive force against the breech face. The case also shows signs of the extractor leaving a significant crease in the rim as well. I find it odd there isn't much flattening of the primer, but then again the case head did fail.

Are you sure that you didn't accidently overcharge the case? It can be real easy to do with a progressive loader. Definitely glad you are not seriously injured.
 
That's odd. I can't imagine what happened, but it looks more to me like an under sized case/excessive headspace issue.

Do you full length size? That rim mark looks to me almost more like it has been slammed explosively against the bolt, and the overstretched brass split.

I believe that your very first step should be to to have your chamber measured and headspace checked, and then, check your dies. To further support that thought, the primer does seem to show some bulging, but not high pressure flattening.

that charge of 4831 should have been nearly a compressed load, I believe, so I;m not entirely convinced that it was a simple overpressure situation, and it just seems so unusual that I'm not really willing to dismiss it as just rupture of an overused case in a bolt rifle. with neck sizing and only a few loads, it probably should not have happened.

What are your thoughts on this theory? come back with your ideas.
 
I know case failures are somewhat rare, but maybe once is enough. So here are all the lessons I learned:

1) Glasses, prescription or otherwise, should be on your face EVERY TIME you pull a trigger. I'm confident they spared my vision to some degree.

2) Check cases for impending head separation if they've been used more than a couple of times.

3) Maybe buying dedicated LH guns is less of an indulgence and more of a wise precaution. I'm certainly thankful this round failed when I was shooting a gun designed to vent gasses away from my hand rather than toward it.
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They don't just happen.

Cases fail, as yours did, because the brass is thinner at that point, caused by stretching. And that's most often caused by sizing the case more than necessary with subsequent repeated firings. Any sizing of the case (the shoulder is the critical part) beyond what is necessary to easily chamber the round in YOUR rifle simply contributes to case streatch. When you size the case, brass flows forward from the case head area which gets thinner as the neck gets longer (or thicker).

Your case failure is not just an insipient case head failure (small crack with some leakage). It's close to a full blown case head seperation, which the strongest rifle isn't likely to withstand. 50,000 lb.s of unleashed energy in your face could be life threatening--vent holes in your receiver won't withstand that.

You could have checked for the crack inside the case with a bent paper clip or similar tool and seen it coming that you keep trimming off.

Can't diagnose your issue with the info I have, but make it a rule to discard any cases that have been necessarily trimmed more than 3 time. I already described where that extra brass came from.

Now it may be that there's more to the issue than I realize, and that you don't need a lecture or any preaching on the subject. And it could be that it happened through no fault of your own. So I'll let my statement stand for any new reloaders out there who might benefit benefit from a brief caveat.

As P.O. Ackley said, you can blow your head off if you don't understand the sizing process. May I suggest Handbook for Shooters and Reloaders, Vol. I and II by P.O. Ackley. Yes, it's old, but a better description of proper sizing and consequences for not understanding the process has not been written.

Just my thoughts on the matter.:cool:;)
 
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It's not an overpressure. The mark on the casehead is from trying 3-4 times to close the bolt on it to extract the case before I figured out the extractor was in the wrong place. It's an abrasion, not a flattening.

Headspace isn't excessive. I size so there's just a tad of resistance to closing the bolt for the very reason some of you mentioned. If anything my ammo is a tad long for the chamber, not too short.

It was a case head separation caused by using a case too many time (which is an act of stupidity) not from an overcharge (which is also stupid, but would have resulted in powder spilling out of the case neck). If there were even a chance it were an overcharge I would have been too embarrassed to ever post anything about it to the internet. :o
 
Need to set them dies to just barely bump that shoulder back.

Excessive headspace can cause failure on the very first loading.
 
Just to make the point again: this was 100% my fault. See point #2 in my original post. The powder measure isn't to blame, the scale isn't to blame and the rifle darned sure isn't to blame. But it wasn't excessive headspace and it wasn't an overcharge. It was failure to check some well used brass to see if it was TOO well used.

If you look at the photo closely you can see that the gap is so big because of flame erosion. Excessive headspace causes it to separate all the way around like it's been cut with a tubing cutter. Believe me, I've seen that happen before with a SMLE.

When I get the chance I'll section the case and post a photo so we'll know for sure. If I'm wrong than I guess I'll have 2X egg on my face :o:o
 
Elkins45, I am glad you were not hurt. Rest assured your lessons are not lost as you have talked me into doing the right thing the next time I reach the range and find I have not brought my shooting glasses. Last trip I forgot them and decided to go ahead and shoot, that won't happen again:eek:
 
I don't see any primer "flattening" from high pressure so I'm guessing the brass was loaded too many times. I loaded mine about five times and threw it away. That was when I had to trim it back to length twice I think.
 
Cases that are FLRS might be the problem. After FLRS several times the cases become thinner at about that point. If you look carefully at such a case before failure you can detect a slight ring around that point. It is more of a problem for belted cases in my experience.

The load used is not a hot load, and is at least 2 grains lighter than I used in my .270s. I don't think it is too high pressure, but looks more like a case failure to me, and if the case has been FLRS several times that is probably the culprit. If the case was resized so that there was excessive headspace it would do that also.

Jerry
 
Glad to hear that you weren't seriously hurt. Looks like the rifle did exactly what it was designed to do and kept the gasses off the shooter. One of the things I like about Savages.

You need to get a paper clip and knock apart the rest of those cartradges and test them for thin walls. I think it's time for me to take out my 270 brass and do the same thing.

Stay safe.
Jim
 
My read on the primer(which is inconclusive),the corners are still round,and I see no crater ring.Its unlikely the pressure was extreme.

I believe you had extreme thinning at the stretch ring,where it separated,before you pulled the trigger.I say that because if you had strong brass in there,and excessive headspace,the primer would setback to the bolt face first,then the case would stretch,and perhaps separate.When that happens,the primers look very flattened.

Assuming you are not picking up range brass,it is very common to create this situation,and unnecessary.

The root cause,very often,is the practice of bumping the sizing die on the shellholder.I understand,your die instructions may recommend this,but its not so good.Each time you do it,the shoulder gets set back excessively.

When the firing pin strikes,the case is driven forward.The case expands with pressure,and grabs the chamber walls.All the stretch occurs at about the rear end of the barrel,as the case head is blown back to the bolt face.

Your brass will last a lot longer if you set the shoulder back only about .002 in a bolt gun.

There is more than one way to measure this.Hornady makes a device that clamps on dial calipers.RCBS makes a Precision Mic,probably the cadillac way to do it.I use a bushing type case gage,such as Wilson sells.You can drop a fired case in it and easily tell if it is within max/min spec,but you can also measure over the case and bushing,together,case unsized,then size till you get .002 change.

I certainly would pull and check the rest of that brass,you don't need an encore performance.

You might try searching for a Varmint Al's website,and check into an article"Finite element analysis of cartridge case stretch vs chamber finish" or something resembling that.It gives a good explanation.

Good luck!You still have both eyes and 10 fingers!!
 
As was said, the firing pin does boot the cartridge forward just a few hundredths upon impact, unless the shoulder is already in solid contact with the chamber front.

The shell starts to expand at the front, and the first part to grab the chamber will be at the front of the case, then the neck, and the case will not be pushed backwards until the expanding gasses start to force the bullet out of the case. This is one of the reasons behind separations related to oversized chambers.
 
Cases that are FLRS might be the problem.
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I shoot the same brass in a number of guns, both bolt and auto loaders, so I have to FLRS each time. Its not proven to be an issue so far, and I usually get around 10 loads out of the brass (commercial brass, not military). Since they dont always "grow" the same, I also trim the cases each time, so everything is the same for consistencies sake. That has also never been an issue.

You need to get a paper clip and knock apart the rest of those cartradges and test them for thin walls.
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That may well show/confirm where you were in the life of that lot of brass. I myself wouldnt shoot any more of it if one cut loose. Personally, once I start getting a sign theres a "ring", and the walls are thinning, I scrap that lot, even if its only one case showing a sign.

My read on the primer(which is inconclusive),the corners are still round,and I see no crater ring.Its unlikely the pressure was extreme.
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I agree, it just looks like the brass was on its last legs.

Assuming you are not picking up range brass...
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While I do pick up pistol brass, I wont pick up rifle brass, unless I know for a fact (ie. witnessed it) its once fired. Pistol brass can be shot to failure with little worry, not so with rifle brass. You need to keep things separated by lots and stay on top of your record keeping, or youre just asking for troubles.


There is more than one way to measure this.Hornady makes a device that clamps on dial calipers.RCBS makes a Precision Mic,probably the cadillac way to do it.I use a bushing type case gage,such as Wilson sells.You can drop a fired case in it and easily tell if it is within max/min spec,but you can also measure over the case and bushing,together,case unsized,then size till you get .002 change.
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I have both of these as well, and mostly use the Wilson gauge. I have used the Hornady headspace gauge to check my die settings, but the few times I used it, setting the dies up by the manuals, the brass always checked out OK, and no other adjustments were necessary.

I certainly would pull and check the rest of that brass,you don't need an encore performance.
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Amen to that.
 
Just a note that belted cases tend to thin more in the head area due to the fact that they headspace on the belt. Manufacturers have tended to be a little sloppy with the chambers and the cases stretch more than rimless cases each time they are fired. I have had to discard belted cases with fewer times resized.
The paper clip test discloses the thin walls.

Jerry
 
Glad you weren't hurt.
Arrived at the range once just in time to see the aftermath of an M1A that got blown to pieces. The RO said the old timers brass looked like he dug it out of the dirt.

With myself and my two sons shooting, we go through a lot of rounds. The investment of time in "simple" reloading is already enough, and I don't wish to take the time to do a "paperclip" test on every piece of brass. So, I decided to strike a balance and not push the envelope- all brass gets fired six times (usually trimming is never even necessary) and then gets set aside for doomsday.
 
It was a case head separation caused by using a case too many time (which is an act of stupidity) not from an overcharge (which is also stupid, but would have resulted in powder spilling out of the case neck). If there were even a chance it were an overcharge I would have been too embarrassed to ever post anything about it to the internet.
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Even when you properly size the case, which you appear to be doing, there's still some case stretch that prevents using the case too many times.
Not a pressure issue, it's thinning out the brass at the case head from resizing. When you fire the case it expands against the chamber walls and forms a seal. However, the case head brass is much thicker and can't grip the chamber walls, so under all that pressure, it stretches backward and slams into the breach face. Repeated firings followed by sizing, which causes the brass to flow forward and get thinner at the case head, will weaken a case until it finally gives.
 
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