Hi-NV Shooter
Gold $$ Contributor
You could measure from the back of the base to the driving band. the main thing is getting a consistent reading. the G3 gauge comes with a test pin so you can always check that you are getting consistent readings.I'm getting ready to start measuring to the first drive band myself, but, in my thinking, the rim thickness is so close, within tenths of a thousandth, (on same box/lot # ammo) that I'm going to try using a regular caliper comparator and measure from base to front drive band, at least initially, to see how it goes.
IMO if we are relying on the case length to always be consistent to measure off the front of the rim, I see no problem with using the base/back of the case.
Lee