Signs of case head separation after only 5 firings?

[bigedp51]

biged, were those cases FL sized before the 1st firing? Sorry SW, I just had to ask, did not mean to get off the subject.

Dgd6mm

Yes they were full length resized before the first firing and every time thereafter with the press reaching cam over. If I remember correctly this was from Reloader Magazine but the amount of shoulder bump was not given.

 

[Savage99]

Bigedp51,

I don't agree that the RCBS gage is all that useful for detecting damaged or unusable brass that may be thinned at the web the way you show it.

The best way is with a heavy wire with a 90 degree hook bent on it's end and shaped to detect too thin a web.

 

[CPorter]

One thing to check but I doubt it is the case. A rough chamber can cause the brass to grab early and expand from the chamber end towards the bolt while the rest is held mostly static. When you full size resize most of this extra length gets shoved into the neck.

 

[SWThomas]

So I did some measuring...

Virgin Lapua measures 1.928" from the shoulder to the base, measured with a bump gauge and a caliper. My fired brass measures 1.934". So it had to grow 0.006" from its first use. I think I can rule out excessive headspace.

I measured the case where the others were showing separation signs and it they measured 0.468". This is with the blade tips of my caliper. After FL sizing it was pretty much the same, maybe 0.001" smaller depending on where I measured it.

I backed the die off and then slowly worked my way back down. I got to where I feel it's just kissing the shoulders and locked it down. I measured with my bump gauge the whole time I was adjusting. So I've got it set to where it's sizing the neck fine but it's not bumping the shoulders at all, according to my measurements.

Sounds like you guys were right and I was either over sizing or I got a bad batch of brass. I guess time will tell.

Does it sound like I got it figured out or should I check something else?

 

[BoydAllen]

You have it. Just for grins, take one case, and size it with the die backed out so that it just sizes the end of the neck, just far enough down to hold a bullet enough to be carefully chambered in the rifle. Load the case with a stout (but safe) load, checking shoulder to head dimension before and after firing. Do this until the case has a noticeably tight bolt close, being sure to keep the back of you lugs lightly greased. It is this maximum shoulder to head dimension that you should be using as a reference when you set your die to bump case shoulders. You should also know that if you are trying to keep your bump small (.001) that you may have some variation of results from the same die setting, so check them all, and make adjustments as needed. Annealing (properly done) is the only way that I know to make your bumps more uniform. When making small adjustments, keep in mind that one full turn of the die moves it up or down about .071 (1"/14).