Case Head Separation

[dave99]

**title should read splitting heads (not necks)**

I am struggling with incipient case head separation on one of the rifles that I reload for.

Basically, I am getting 2-3 firings, and getting a stretch mark near the case head. In a couple of instances, it has progressed to a full case head separation. The point of incipient (or full) separation is consistent.

Details:
Factory T3 Tikka in 30.06. Approx 2008 production.
Brass: have seen this with Federal as well as Lapua.
Load: does not seem to matter. From a very mild 165gr SST over 52.5gr IMR4350, to a stouter 180gr Accubond over 55.5gr IMR4350.
Primers: Fed 210M and CCI
Resizing: lightly lubed cases sent thru RCBS 2-piece full resize.

Primers tend to be fairly flattened, but no real ejector marks on the brass.

Can anyone enlighten me on why this is occurring and how to avoid? I would expect to get much more than 2-3 firings on quality brass under moderate pressure loads.

I cannot take pictures because I don’t have the rifle or brass at the moment. In a couple weeks I will have some pictures to post of primers and case heads.


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[catnthehat]

Jeepers, so many things could be the culprit from the diess themselves to the way you are resizing, to headspace issues.
Have you miked the various unfired, fired and resized cases to check thee difference?
Cat

[DLab]

Full length sizing your brass too much creating excessive head space in the chamber by setting the shoulder back too far?

[Dubious]

Check head space with go/no go/field gauges. If you don’t have then take a trip to the gun smith and have him check it. Have see this issue with ackley chambers in the past was solved by using a false shoulder when fire forming brass.

[Dean2]

99.9% you are way over sizing your brass. My bet is you have the die turned down till it touches or almost touches your shell holder. If I am correct, with brass you have shot in this gun, back your full length sizing die off 1 full turn. Presto, no more head separation.

[spurly]

Originally Posted by Dean2

99.9% you are way over sizing your brass. My bet is you have the die turned down till it touches or almost touches your shell holder. If I am correct, with brass you have shot in this gun, back your full length sizing die off 1 full turn. Presto, no more head separation.

This

[58thecat]

Originally Posted by Dean2

99.9% you are way over sizing your brass. My bet is you have the die turned down till it touches or almost touches your shell holder. If I am correct, with brass you have shot in this gun, back your full length sizing die off 1 full turn. Presto, no more head separation.

yup and toss the others out and get a fresh start....if a few in a lot are suspect, cracked, separated toss out the other brass too of it will p you in the arze in the field.

[bdub]

Went through this once with a rifle in 300 WTBY chambering. Tried everything reloading wise looking for a solution and wasted a lot of time and effort. It was a headspace issue in the end.

[Sashi]

Check to see if the stretching starts with factory ammo, If it does sell the rifle to someone who doesn't reload.

[amosfella]

Problem #1 could be that the brass is being over resized. Might have to reset your dies in your press. You only really want to bump the case shoulders back about 0.005"

Problem #2 Could be a rifle headspace issue. You can measure your fired cases to see approximately if it's out or not.

Not a popular opinion here, but you can deal with an overlength chamber by just neck sizing then bumping the shoulders back once in a while if the bolt gets hard to cycle. Or keep neck sizing even after the brass is a touch too long to the shoulder. A friend of mine does that, and he runs massively over pressured rounds. We've sawn cases loaded that way in half after 30 rounds and the cases aren't weakened from a physical structure standpoint. The cases only seem to weaken from the sizing down and expansion to fit the chamber from being fired. That causes the brass to 'flow'. If the brass doesn't 'flow', the case doesn't weaken. We were having to anneal case necks though.

Problem #3 could be that the case from the neck to the middle of the body isn't moving backwards enough in the chamber when fired. This causes the casing to stretch just above the head instead of the whole length of the body and causes rapid head separation. If you have a borescope, look and see how rough the chamber is. If you don't, straighten out a paperclip and bend about 1/8" to 90*, and feel inside the chamber and see how rough it feels.

[elkhunter11]

There could be multiple issues but I would suspect overworking the cases, by pushing the shoulder back too far. I set my dies to only push the shoulder back enough to be able to chamber the sized case without resistance.

[bdub]

If its a headspace issue most of the damage will be done on the first firing of virgin brass. If you have a once fired case cut it in half lengthwise. You should see signs of incipent case head separation starting on one firing if its a headspace issue.

[Dean2]

A lot of talk about headspace, and while it is possible as a cause in some rifles, we are talking a relatively new Tikka of modern manufacture. I have never seen a Sako or Tikka with excess headspace. I guess it is possible but I would be tremendously surprised if a Tikka got out of the factory with excess head space.

[bdub]

This is what I was getting on first firing on the rifle with headspace issues.


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[Battle Rat]

It would be interesting to measure a chamber cast compared to the sizer die cast.

[Pathfinder76]

90% of case head separation is loader induced. Max chambers with min dies can exacerbate the problem im sure.

[Cheyenne 1]

This is about as accurate and as simple as it is.
Very well explained and no excessive sizing.
Die, chamber, press, shell holder are all part of the equation.
That’s why you have to measure. All the die setting instructions should be burnt.
https://www.youtube.com/watch?v=WfWS7R1CdZI

[dave99]

Thanks for the input everyone. It is incredible to have so much experience weigh in.

To answer a few questions:

- I do not recall any separations or incipients on first firing of handloads or with new loaded ammo (although it has been years since I have fired store bought loaded ammo out of this rifle). All separations have occurred on 2nd and 3rd firing, and I don’t recall having ever resized brass for this rifle more than twice before discarding due to separation.

I had assumed that it was weakening on every consecutive firing beginning with the FIRST and eventually separating. The diagnostic test of using the paperclip method to check for weakening after the first firing would rule out a headspace issue if no thinning occurred after this first firing. Am I correct on this?

- My brass resizing (I only FL resize because I simplistically decided long ago that I prefer easy problem free feeding over brass life -although this is certainly up for debate) involves removing the FL sizing die from its case, and following these steps:



I do not ever recall setting up anything more involved than these steps for the resizer die :/


Question: by calling brass OVER WORKED, do you mean that the shoulder is pushed back further than needed on FL resize, such that it stretches a long ways on firing, only to be pushed back on resizing, eventually causing thinning and separation?

It sounds to me like this is the issue.


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[dave99]

A member asked via PM what my seating process is like, since I may be pushing the shoulder back with an improperly set up seater.

Here it is:






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[Pathfinder76]

It is your sizing die, not your seating die. To really know what you are doing to brass in relation to your chamber you need tools that will allow you to measure how much you are moving brass. These tools are cheap and should be in every reloading bench.

[Salavee]

No matter how you set up your die, it's guaranteed it will not resize all the way to the belt, leaving you with a bit of a bulge above the belt that get progressivly worse.
I suggest you check out Innovative Technologies website and have a look at his belted magnum resizing die.

[elkhunter11]

Originally Posted by dave99

Thanks for the input everyone. It is incredible to have so much experience weigh in.

To answer a few questions:

- I do not recall any separations or incipients on first firing of handloads or with new loaded ammo (although it has been years since I have fired store bought loaded ammo out of this rifle). All separations have occurred on 2nd and 3rd firing, and I don’t recall having ever resized brass for this rifle more than twice before discarding due to separation.

I had assumed that it was weakening on every consecutive firing beginning with the FIRST and eventually separating. The diagnostic test of using the paperclip method to check for weakening after the first firing would rule out a headspace issue if no thinning occurred after this first firing. Am I correct on this?

- My brass resizing (I only FL resize because I simplistically decided long ago that I prefer easy problem free feeding over brass life -although this is certainly up for debate) involves removing the FL sizing die from its case, and following these steps:



I do not ever recall setting up anything more involved than these steps for the resizer die :/


Question: by calling brass OVER WORKED, do you mean that the shoulder is pushed back further than needed on FL resize, such that it stretches a long ways on firing, only to be pushed back on resizing, eventually causing thinning and separation?

It sounds to me like this is the issue.


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Instead of preloading the die, I actually back the sizing die off 1/4 -1/2 turn or so, from the shellholder, and chamber a sized case . If there is resistance closing the bolt, I turn the die down a couple of thousandths, and size another case, and chamber it. I adjust the die towards the shell holder in these small increments, until the resistance disappears, then set the lock ring. Depending on the die and the chamber, there may be a noticeable gap between the die and shellholder, or there may be no gap.

[Dean2]

Originally Posted by Salavee

No matter how you set up your die, it's guaranteed it will not resize all the way to the belt, leaving you with a bit of a bulge above the belt that get progressivly worse.
I suggest you check out Innovative Technologies website and have a look at his belted magnum resizing die.

He is loading a 3006. No belt on those.

To the op, if you are following those instructions then my post above is dead on. Back you seating die out 1 1/2 turns from where you have it set. You are WAY over sizing the brass and creating your own headspace problem. Yes, u are over stretching the brass on each successive firing.

[dave99]

Originally Posted by Dean2

He is loading a 3006. No belt on those.



To the op, if you are following those instructions then my post above is dead on. Back you seating die out 1 1/2 turns from where you have it set. You are WAY over sizing the brass and creating your own headspace problem. Yes, u are over stretching the brass on each successive firing.

Ok, I will certainly try this on the next batch of brass.




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[Dean2]

Originally Posted by dave99

Ok, I will certainly try this on the next batch of brass.




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Sure you know but I meant the sizing die.

[dave99]

Originally Posted by Dean2

Sure you know but I meant the sizing die.

Yup. Thanks. Sizing die setup is the problem, not the seating die.


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[dave99]

Originally Posted by chuck

It is your sizing die, not your seating die. To really know what you are doing to brass in relation to your chamber you need tools that will allow you to measure how much you are moving brass. These tools are cheap and should be in every reloading bench.

Thanks Chuck. I should look at picking up some of those tools. The video link that Cheyenne 1 posted offers a great rationale for testing with tools as well as by feel.

As it turns out, I have done neither up to this point. Lesson learned.


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[Salavee]

No matter how you set up your die, it's guaranteed it will not resize all the way to the belt, leaving you with a bit of a bulge above the belt that get progressivly worse.
I suggest you check out Innovative Technologies website and have a look at his belted magnum resizing die.


Sorry ... missed the 30 -06 part.

[abhunter8]

Very good information, thank you. I had the exact same issue with a Remington 700BDL 7mm Rem mag I traded for. It was one of 4 rifles I was reloading for and had brand new Hornady dies and I couldn't figure out why is was getting full blown case separation, cracked and stuck cases after 2 full length sizes. Has never happened with any other rifle or reloading setup. I no longer have that rifle or those dies and the guy I gave it to doesn't reload.

[bdub]

Originally Posted by abhunter8

Very good information, thank you. I had the exact same issue with a Remington 700BDL 7mm Rem mag I traded for. It was one of 4 rifles I was reloading for and had brand new Hornady dies and I couldn't figure out why is was getting full blown case separation, cracked and stuck cases after 2 full length sizes. Has never happened with any other rifle or reloading setup. I no longer have that rifle or those dies and the guy I gave it to doesn't reload.

The rifle I was having issues with was also a Remington. Even with full length resizing and under max loads a guy should get more than 2 reloads. The cure was either have the gunsmith screw around with the existing barrel or rplace the barrel. Cost wise I should have just sold to someone who doesn’t reload but ended up putting a new tube on it.