Detail. Expander (NOE) 308, sized GC bullet (168gr) 310, mic'd. Fired case OD 0.336 ID 0.312 neck thickness 0.012. So neck expanded 004, assume 002 shrink of brass. Tends to indicate the bullet expanded to 314 before hitting the throat and bore. Saw a lot of lead 'rings' when cleaning these. Theorize: Alloy is getting pushed to the base (expanded to 314), where it is getting cut off by the GC that doesn't expand (as much?). Explains 'ring' attached to mouth. Thoughts? I will repeat with more paint on neck to find real max ID of chamber neck. Also shows that case gauge is not real accurate measuring shoulder position (case length/HS) for setting sizer die. Datum points are different.
Assuming that the chamber does not have a 'step' for the shoulder the only real possibility is the Lee sizer and the chamber do NOT have the same shoulder angle (and even hot loads won't change the fired shoulder to the chamber angle). I also observe the 'rings' of alloy are only 270* so the case is not aligned with the chamber, i.e. case flops around. Case that was sized shows no marks on the case body from sizer, NOT sized down! A chamber pound cast will not show any of these problems!Edit: annealed a case dead soft, flared mouth and inserted into chamber. Mouth is 338 so 336 max neck OD. Minus 012 for neck thickness, bullet should be sized 312. I'll go with 311 for CVA SS and 310 in AR pistol. I don't use bore riding moulds so don't care where the rifling starts.
Edit: AR pistol is 336 neck ID so 310 bullets.