6PPC Case Separation

[jcullen]

What would cause the case to separate at the neck, case fired about ten times and not with hot loads. these are Lapua 220 Russian fire formed and turned to .262......JC

 

[Eddie Harren]

I have seen this on occasion, over the last 20 years. Some think that it is the result of cutting to far up on the shoulder when turning necks. Others say it is a result of 'doughnut' removal. I have never had this experience. Sounds like it is time for some new cases.

 

[fdshuster]

jcullen: I'm not saying it's what happened: strange things do, but when the case necks were outside neck turned, could the cutter have taken a cut into the shoulder, just to the rear of the shoulder/neck joint? Is it possible to cut the case,s) lengthwise and see how thick the brass is at the point where the seperation is? I know with my .262' chamber neck I must turn the Lapua to .0085' neck wall thickness and can see where just a little too far down the case neck will cut into the beginning of the shoulder. Additional note: Just read doced's response after posting mine. No, I've never seen it either and I'm up to 30+ reloads on a few of my older Lapua cases: no problems- yet. Still would lean toward thinking the cut was taken too far back, and into the shoulder. Let us know what you find.

 

[rayjay]

Whenever I am setting up to neck turn a cartridge for the first time I section the first case to see if I have plenty of metal left where it is supposed to be.

ETA: Here is a thread I did about case sectioning. You can see the case on the right has a uniform progression of cross section from the neck through to the shoulder.

http://6mmbr.websitetoolbox.com/post?id=2903201