Casehead seperation

[navy1942]

I was doing my final work up on the ASW 338 with 300gr Lapua Scenars, using H1000 and Vhitavouri N570. The ladder test got me to 92.6 and 93 of N570 and 93 of H1000, though 93.6 of H1000 was the next best. So I loaded up 5 rounds of each for the final selections. The good news is 92.6gr of N570 is .34 MOA at 200 yards with 5 rounds average FPS 2866.8, Extreme spread 15 and Standard deviation of 6.

2 lessons I learned.
1st - During ladder testing decide very carefully if the hottest load is really in the node or maybe an accident of shooter movement.

2nd - 5 or 6 hot loads and full length sizing are about all the lapua brass casehead can take so make sure you segregate cases used for hot loads from the cases used for standard loads.

I'm just glad I tested the hottest load last.

One other thing I would like opinions on: In order to eliminate heating as a factor, I nestled the action area ontop of those blue ice packs while shooting and put one on the barrel for 5 minutes between strings. Has anyone else tried that?

 

[targaflorio]

Re: Casehead seperation

I would like to see photos of the caseheads of your hottest loads. Are you seeing flat primers and/or any ejector marks? I'm finding that in my 300 win, my hottest loads shoot best.

 

[turbo54]

Re: Casehead seperation

It's been my experience CHS is a function of brass sizing, and not so much pressure.

I've never messed with your cartridge, but in those I have loaded for, primer pockets get loose from high pressure loadings, and CHSs come from oversizing cases, causing them to stretch at the web upon firing.

 

[ChrisGarrett]

Re: Casehead seperation

That is the first time in over six years of posting about and reading posts about the 338LM, where I've seen, or read of, case head separation.

Lots of people shoot hot loads, but I've never heard about it happening.

Congrats, you're that guy!

You might be resizing too much. I mostly neck size my 338LM brass (Lapua/Norma) and I have the Hornady/Stoney Point headspace gages to measure things.

With some of my cases, I'm at 12 cycles with moderately warm rounds, with some hot ones sprinkled in for good measure.

Chris

 

[BuzzBoss915]

Re: Casehead seperation

Case head separation is almost always because of <span style="text-decoration: underline">excessive headspace</span>, at least where I come from. There are a few reliable signs you will notice caused by excessive pressure. Flat primers, loose primer pockets, and especially extractor marks on the case head. That's all I know about the subject and I don't own a 338LM, BTW.
BB

 

[navy1942]

Re: Casehead seperation

Targaflorio,
Sorry I already tossed them, but to answer your question: the primers still had rounded edges but were not loose in any fashion and they did have very light ejector circles. Nothing that would have caused me concern. What got my attention first was the very sticky bolt. However, I attributed that to the the case head expansion.

 

[navy1942]

Re: Casehead seperation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChrisGarrett</div><div class="ubbcode-body">That is the first time in over six years of posting about and reading posts about the 338LM, where I've seen, or read of, case head separation.

Lots of people shoot hot loads, but I've never heard about it happening.

Congrats, you're that guy!

You might be resizing too much. I mostly neck size my 338LM brass (Lapua/Norma) and I have the Hornady/Stoney Point headspace gages to measure things.

Of course I am

As my wife will attest, even when it can't be broken, I will be the one to break it!
I have to admit I always FLS, but it looks like that is coming to an end.... I will have to break out the neck sizer.

With some of my cases, I'm at 12 cycles with moderately warm rounds, with some hot ones sprinkled in for good measure.

Chris </div></div>

 

[former naval person]

Re: Casehead seperation

Oversizing. That is it. Period. Setting the shoulder back too much each time...That is it. Period. Repeat...don't set the shoulder back that much each time. Period...shall I say it again...you need to work on setting your die for no more than .002 shoulder bumping. Basic reloading 101. JMHO

 

[turbo54]

Re: Casehead seperation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">Oversizing. That is it. Period. Setting the shoulder back too much each time...That is it. Period. Repeat...don't set the shoulder back that much each time. Period...shall I say it again...you need to work on setting your die for no more than .002 shoulder bumping. Basic reloading 101. JMHO </div></div>

What do you mean?

 

[ChrisGarrett]

Re: Casehead seperation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: navy1942</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChrisGarrett</div><div class="ubbcode-body">That is the first time in over six years of posting about and reading posts about the 338LM, where I've seen, or read of, case head separation.

Lots of people shoot hot loads, but I've never heard about it happening.

Congrats, you're that guy!

You might be resizing too much. I mostly neck size my 338LM brass (Lapua/Norma) and I have the Hornady/Stoney Point headspace gages to measure things.

Of course I am

As my wife will attest, even when it can't be broken, I will be the one to break it!
I have to admit I always FLS, but it looks like that is coming to an end.... I will have to break out the neck sizer.

With some of my cases, I'm at 12 cycles with moderately warm rounds, with some hot ones sprinkled in for good measure.

Chris </div></div> </div></div>

Personally, if I ever became Supreme Dictator Of Earth, I'd decree that every reloader would have to purchase the Hornady/Sinclair type headspace gages, before they could load a single rife round.

There are other ways to figure things out, but the HS gages are fast as hell. You buy a set for $40-$45 and you can do just about every bottle neck cartridge known to man.

They take all of the guess work out of setting up a sizing die and properly sizing a case.

Chris

 

[navy1942]

Re: Casehead seperation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">Oversizing. That is it. Period. Setting the shoulder back too much each time...That is it. Period. Repeat...don't set the shoulder back that much each time. Period...shall I say it again...you need to work on setting your die for no more than .002 shoulder bumping. Basic reloading 101. JMHO</div></div>

I have taken note and learned the lesson. Besides, who am I to argue with an Officer who actually worked for a living!