.284 Chamber Questions

[can1010]

Case head separation is ONLY caused by pushing the shoulder back excessively, on the order of .005" or more.

You do realise you cannot size the solid head portion of the case, right?
As long as the shoulder is pushed back .002" and the body is reduced on the expansion ring .002", you should have perfect chambering and no chance of a head separation.

Hope this helps.

Cheers.

the problem is the brass being .4945-.495 when new and blowing out to .499 on first firing then some dies sizing it back down .496 then after multiple firings it will crack like case head separation even with minimal shoulder bump. that is why the first post was asking about different reamers. I had Bartram brass crack in five firings switched to Whidden die and it holds the case to .500 without sizing it and it solved my problem no more case head separation.

 

[MagnumManiac]

I honestly do not think the expansion of the brass is/was the problem. It has to stretch FORWARD to cause thinning as well as sideways.

I shot a 6.5-284 Norma in 3 seasons of F-Class. The same batch of 100 Lapua cases were used.
I used a Forster FL Bushing die with honed neck and pushed the shoulder to chamber size, the body was reduced .005" by this die and with over 20 sizings on each piece I never had a problem.
Maybe the CIP spec reamer took this into consideration.

Just as a side note, I have a generously sized 25-06 chamber that expands new brass on the order of .020" over new on the expansion line, I have brass that has been sized 8 times with standard RCBS FL dies and have never had a head separation of any kind, granted the LENGTH of the chamber is tight, it is .001" above SAAMI minimum in headspace spec.

Cheers.