I had to inspect the case very very closely to see the line in the sharpie that the chamber contact created because it looked like it was right on the corner of the chamber neck shoulder junction.
I found some interesting things last night in sizing cases and taking measurements and trying them in the chamber after sizing. It's hard to explain without pictures, but I'll try.
Using my Hornady case comparator, I shoot for a sized measurement of 1.809. this gives 0.003 shoulder setback for my chamber.
When sizing with the expander ball in the die, the neck diameter near the shoulder junction is increased quite a bit and I'd get stiff chambering even when the comparator showed 1.809. I pulled the expander ball and sized a case which came out to 1.807 or so with a uniform neck diameter across the whole neck. That case chambered freely. So I thought maybe the expander ball was screwing things up when pulling it back through the smaller neck.
I adjusted the die without the expander ball installed to give 1.808 or 1.809 and sized a few cases.
I then took my Lyman M neck expander die and expanded the necks on those after using the FL die without expander ball. The comparator measurement grew to 1.809-1.810 and also increased the neck diameter near the neck junction a bit!! These cases chambered pretty freely for the most part.
So what I found was that for some reason, even when using the Lyman M expander separately, is that the shoulder is being moved upward (or lengthening?) to some degree when expanding the neck, which happens to a greater degree when using the expander ball. It seems that the shoulder might be moving more closer to the neck in comparison to where my comparator tool hits the shoulder.
I have no idea why this happens, but I don't like it. It never happened that I'm aware of with Peterson brass. It could be the fireforming process pushing more of the shoulder material into the neck and junction area than what happened with the Peterson. I'm not sure if it's a function of the brass or if it's due to my fireforming. I did have some wonky cases that didn't chamber quite normally when fireforming, so it is either that or the brass itself. The Lapua also takes about 2 seconds longer in my induction annealer to glow compared to the Peterson.
A note on the contact you're seeing around the 0.200 line. I had a faint mark there in mine as well, just on one side and in a small spot when I sharpied the whole case. My measurements indicate I definitely have clearance there, so I think the mark/rubbing might be from the ejector pin pushing the case sideways the tiniest amount. I only saw it on a case where I only had 0.001 clearance, so it wouldn't take much cant of the case to cause contact there.
Last edited:
. I don't see how you guys keep up with it all
