The brass is all new. Bought it a couple years ago and ran it through the tumbler, but got sidetracked on other projects. Ran it through a FL sizer a couple weeks ago, but don't think that did more than round the mouths. Pretty sure I didn't touch the shoulder.

While the headspace is near maximum, the dimensions laser etched in my go and no go gages are only .003 apart. I only measured .0025 difference, but probably checked it at a different diameter on the shoulder with a cheap caliper. The bolt will start to close on the no go, but won't quite go all the way down.

I really think the issue is a combination of the dished bolt face, a firing pin that's sharp and has the protrusion at minimum(.035) and the new brass being short. Found my old magnifying glass and the primers look a little domed and a little cratered too, but not pierced. The outer edge might be past the brass, but my old eyes can't see that close. Dug up some Winchester brass that was run through this rifle a few years ago when it was built. It showed some of the same symptoms, but to a lesser degree. The LC brass is part of it.

Got the bolt head on order from Midway(needed a new mag box too). Hopefully, this one will be flat. When it comes in, I'll tighten the headspace , move the pin protrusion out a little and jam some bullets about .020. Might even try dulling the firing pin. It might take a few weeks to get to the range, but I'll let you know.

Thanks.