Case splitting after fired...

[Tvaughan]

I'm getting case head separation, I have reloaded them quite a few times (.338lm)
I have reloaded approx 40 rounds and I am not sure if I should keep shooting (my guess is no) but I can't really tell which ones have symptoms, they all have a light shine where the resizing die stops. Should I just trash them all? Most have been reloaded 6+ times others have been reloaded 3-4. Thanks guys

 

[newmexkid]

Do the paper clip method on the inside of the cases. Oh, they are loaded!

 

[rcoody]

what is the difference in the measurement from base to shoulder datum between your fired brass and resized brass?
if it is more than .002 then trash them and adjust your die for the proper shoulder bump.

 

[Rich Coyle]

Too much headspace.

 

[Deleted member 46119]

What brand of brass?

Do you anneal? Note: no annealing means different parts of the brass get worked.

4 times + reloading for a 338LM is not bad.

I would pull the bullets and start over. Paperclip method.

 

[Pdvdh]

You can look down into the empty case with a flashlight and see the extent of the thinning on the interior of the casing, about 3/16" above your reloading die's edge of contact near the base of the case. You'll see the concave ring where the casing sidewall is distinctively thinned. Will be a concave ring visible.

The primary error to get premature case head separation is if you're setting the shoulder back too much when resizing the fired cases in your resizing die. You adjust your sizing die so the shoulder is only shoved back maybe 0.002" from the fired case shoulder length.

You should also be able to see the incipient separation ring (again about 3/16" above the lowest contact point with your resizing die) on the exterior of the casing. It will be an exact location match to the hollow concave shadow visible within the interior of the cases. Except the exterior ring will be a brighter line around the exterior of the casing.

 

[rcoody]

What brand of brass?

Do you anneal? Note: no annealing means different parts of the brass get worked.

4 times + reloading for a 338LM is not bad.

I would pull the bullets and start over. Paperclip method.

actually properly sized lapua brass should be good for 10 or more firings

 

[bigedp51]

Your shoulder bump is your head clearance when the cartridge is chambered. And if you push the case shoulder back too far when full length sizing you create too much head clearance. The excessive head clearance allows the brass to stretch beyond its elastic limits and causes case head separations.

If you measure a "fired" case with a Hornady cartridge case headspace gauge and then set your die up for .001 to .002 shoulder bump the brass can't stretch and thin.

Below measuring a "FIRED" case from my AR15 rifle, and then I set the die up for .003 shoulder bump.

Below is a exaggerated drawing of full length resizing, and you want to size the case .001 to .002 below the red dotted line. The more you push the case shoulder back toward the green dotted line the greater chance of case head separations.

The quality of the brass, chamber diameter and headspace/head clearance governs how long the case will last.

 

[Pdvdh]

actually properly sized lapua brass should be good for 10 or more firings

Yup.

 

[BHC]

I cant add any technical info. But, my friend let me shoot his custom 338 lm. First shot and cracked case just like you had. His was Lapua brass.

 

[cape cove]

Regardless what make of brass you are using if your sizing die isn't adjusted right the cases will not last.

 

[Pdvdh]

And it's nearly impossible to get the case head separation with a properly adjusted die. Shy of defective brass manufacture, or mismatched chamber diameter and sizing die diameter.

 

[Buck Buster]

I have two magnum rifles, a 308 Norma and a 300 win. mag. all I do is neck size each. They fire form to the inside of the chamber, the bolt works a little bit stiff but the brass lasts a long time. I have never had a head separation only split necks in time, when they start to split they get thrown out. Good luck hunting and be safe.

 

[Adikted]

The only thing I would add to the above information is to say that if you have excess headspace then you've been overworking the brass in your sizing die up to this point making it brittle, adjusting your dies won't save them, it'll just help with the next batch

Had similar issues with a 300 win mag, found the head space was .011 over Sami minimum, case life was 3 shots