Thanks for your comment, I could get four gauges for each of the three calibers I currently load for $60 plus shipping, or a big set on Amazon for $120 with free shipping that would cover just about everything. Still wish there was a cheaper way.
I agree with you about not being able to change the diameter without lapping, but knowing the precise diameter would still let me know what the tension would be for different thicknesses of brass, and the stock RCBS die might coincidentally happen to be a good match "as-is" for one type of brass...
I contacted RCBS recently because I couldn't find any published specs on their full-length sizing die neck diameters. They were kind enough to provide the following info:
6.5 Creedmoor .283 +- .002"
270 Winchester .298 +- .002"
7mm-08 .303 +- .002"
I was surprised RCBS does not hold them to...
Thanks for your input. I don't think the shell holder is moving. The cartridge base is sliding partially out of the shell holder. I went with the Lee shell holder set since it was very affordable compared to the RCBS. I've ordered the RCBS shell holder and I should have it in a couple weeks...