My first Lapua case head separation

[kelbro]

I'm guessing about 12-15 loads on this case. Setback has always been .001-.002. Large primer 308. Might have been at the edge of high pressure once or twice during load development, who knows.

I was not really checking for this. I was weighing H2O capacity and realized that the case was 'leaking'! What an eye opener.

Checked the rest of the batch and didn't find any more. I need to be more judicious about checking and scrapping brass.

 

[6.5 forever]

Yup it would be wise to include case inspection in you reloading process

 

[old_heli_logger]

This is a great reminder for me. Thank you!!

 

[kelbro]

Checked the velocity log for that batch of loads and there was no variation in fps for that particular load.

My normal routine when I get back from the range is to drop the brass into the tumbler to run for an hour. That might possibly mask a visual indicator.

I'll be using my pick from now on.

 

[Janeau]

Typically .308 case show sign around 6-8 firings. That you had 12-15firings before it gave up is already over expected lifespan. But this show that your case inspection procedures are lacking..case separation warning are present way before it happen.

 

[Tesoro]

Post an enlarged pic of the base of case

 

[LRPV]

Maybe you already are but if I were you I would re check my sizing operation to my chamber fitment. I know at times that what I thought was a .002" bump was indeed more because when I measured, the case hadn't grown enough to be a tight fit lengthwise in the chamber yet. Once the base was sized on the brass with no shoulder bump the bolt would fall on the brass. Just something to think about. I know guys get well over 50 loads on BR brass and I can't imagine 308 is much different, but I've been wrong before.

 

[M-61]

Setback has always been .001-.002

What was the purpose of ‘setback- shoulder bump’? Why? Bolt not closing? Bolt required excessive effort to close?

 

[M-61]

Setback has always been .001-.002

What was the purpose of ‘setback- shoulder bump’? Why? Bolt not closing? Bolt required excessive effort to close?

 

[Kracken McGraw]

It’s really a wonder why that didn’t pull apart on the last firing in you chamber.

 

[Steve Donlon]

Do you check your brass before sizing to see if it needs to have the shoulder pushed back and if so how much? I use a body die with a Lee lock ring with the rubber O-ring so I can adjust how much set back each case gets when needed.

 

[Dgd6mm]

Im sorry but I find it hard to believe that if everything is right with brass to chamber fit with die being properly set up to resize to the chamber that Lapua brass will fail 12-15 firings.

 

[BoydAllen]

Three things: I gauge shoulder bump relative to the longest datum to head dimension that can be created by neck sizing hottish loads three or more times, until there is no increase. I also can work with once fired by making a too long case using Scotch tape, and working it down very gradually. I fire a given batch of cases in rotation so that work hardening will be relatively consistent. Finally, I check the bump from time to time during a sizing session, to make sure I am getting what I want.

 

[Alex Wheeler]

You should never get case head seperation. The brass was either stretched a lot on the first firing or your bumping more than you think.

 

[Syncrowave]

Something about that case just looks wack to me. Are you using a small-base FL RS die?

 

[LRPV]

Any chance that you picked up someone else's brass one time by accident?

 

[Straightshooter1]

I'm guessing about 12-15 loads on this case. Setback has always been .001-.002. Large primer 308. Might have been at the edge of high pressure once or twice during load development, who knows.

I very much doubt that "edge of high pressure" had any to do with it. I run my .308 cartridges regularly up near max and so far my Lapua SRP cases show no signs of separation after 18 firings. Likewise, I've got 19 firings on my 6.5 PRC Lapua cases with no separation signs. Just thought this might give you some perspective.

I was not really checking for this. I was weighing H2O capacity and realized that the case was 'leaking'! What an eye opener.

When I first started reloading for my .308, using Federal brass, I also was not really checking for it and got some of that case head separation at 9 firings. Since then, I've always made it a point to check for it after every resizing session.

I found that the reason I had this issue was my die setting was actually setting the shoulders back more than I thought.

Checked the rest of the batch and didn't find any more. I need to be more judicious about checking and scrapping brass.

View attachment 1760686

Hmmm??? What's the method you use to check for that?

 

[mic2377]

How much were you bumping the shoulder each firing? Surprised these did not last longer.

When I first started reloading I was using RCBS 308 full length dies and the sizing by running the die right down to the stock shellholder. I was shooting LC cases in a AR-10.

Turns out that it was bumping the shoulder something like .005-.006 each firing (IE WAY too much bump). Should have known due to the frequent need for trimming the cases.

Despite this, I got 8-9 firings out of these, and they were retired not due to case head separation, but due to inconsistent neck tension related to work hardening (yes in hindsight, they could have been annealed).

So curious to hear about the sizing practices and pressure of the loads.

 

[Murray Brook]

Something about that case just looks wack to me. Are you using a small-base FL RS die?

I tend to agree with you. Anytime I've seen this it was never as straight lined as this and always a little further up the case. JME

 

[kelbro]

I'll try to answer as many questions as possible...

1. Dies are Redding bushing FL dies.
2. Shilen Select Match barrel with F/TR chamber. Brass sizes very easily so not a lot of expansion.
3. Shoulder bump is measured using a RCBS precision micrometer which mirrors the Hornady measurements. Measure before sizing, measure after sizing.
4. It's possible that there are more firings on that piece of brass than 12-15, that's an estimate. Never had this happen before so tracking is lacking.
5. The way that I do load development, some cases may get used once or twice more than others in the same batch of 100.
6. There was one batch of 40 that was sized .004-.005 shoulder bump due to me using the wrong Redding competition shellholder.
7. This brass has been trimmed once and it was not a significant amount trimmed.
8. I have a sharp pointed pick that is a part of the RCBS Case Master Gauging tool. I have not been checking them because I have not seen any indicators of this before on this brass.