(09-28-2021, 07:45 PM)Lemonaid Wrote: The pics remind me of questions some have had with cases after sizing, concerned about case head separation. It looks to me you have an bit of frosting from your chamber that stops at the case head as it is mostly solid brass. On highly over pressure brass, the case head can expand but that should be easy to check. Measure case head on unfired brass and compare. I think you would see some obvious pressures signs, ejector marks, extractor marks and primer flattening if were hot enough to expand the case head.
I posted those pictures I found online. I'm not familiar with the term "belting" and posted the pictures to clarify. Sorry for the confusion.
My thought was if the Starline brass is a bit brittle, shrinking it down .035"+ and headspacing 8 or 9 thousandths might cause work hardening above the webbing.