CH4D is a great company and without them I could never have shot so many BPCRs over the years. When I compare my cases following full-length sizing, they were a perfect match for the specs I pull from Cartridges of the World. So, I believe the dies are correct.

My question is why is the old cartridge's neck narrower than specs and working great for for this rifle? Are the dimensions of the chamber correct and I am missing something?

At this point, I am looking at having the neck opened and staying with the dies I have now.

Thanks,
Randy