“All I can say is it worked fabulous!”
In my opinion, grinding the bottom of the die and or top of the shell holder is a bad habit, again, my opinion, it is possible to determine if the press restored a case to minimum length/full length sized the case before the ram is lowered. The part of the case that does not get stuffed into the die will be hanging out between the die and shell holder, meaning, the case will hold the die off the shell holder if all of the case is not sized. Then there is that part were the WSM cases take a hammering when fired. To size a case the press must have the ability to overcome the case’s ability to resist sizing. Lowering the die an additional fractional turn of the die increases the presses ability to overcome resistance to sizing.
Before lowering the ram, measure the gap between the die and shell holder with the ram up, if there is a gap measure the gap with a feeler gage (some of the more talented use light), again, if there is a gap the case won, the case whipped the press, to increase the presses ability to overcome resistance screw the die down an additional fractional turn.
I size cases for short chambers without grinding the die and or shell holder, I change the deck height of the shell holder, RCBS shell holders allow for the case to be raised in the shell holder .012” for most of the cases I work with.
Must be understood!: The limit to sizing is controlled by contact between the die and shell holder. Your smith purchased a go-gage, in the hands of most smiths and reloaders, a very useless tool, your smith could have removed the primer punch/neck sizer plug from the die then used the go-gage to check the distance from the deck of the shell holder to the shoulder of the sizer die to determine of the die/shell holder combination had the ability to restore the case to minimum length, again, once the die contacts the top of the shell holder,’that is it’. The go-gage should be chamber go-gage length, the gap between the bottom of the die and top of the shell holder when the go-gage is installed in the shell holder with the ram up should indicate the difference between a minimum length case and a go gage length chamber when measured from the usual places.
Usual places: Case, from the head of the case to the shoulder/datum. Chamber, from the bolt face to the shoulder of the chamber/datum.