You're right, Chuck, that trial and error regulation by hand is reserved only for the highest grades (if they even still do it at all). I understand in days gone by the owner could have the opportunity to participate in regulation, and old labels inside case lids told the owner what load the gun had been regulated for - not just for DRs, but shotguns, too. In a 12 it was commonly 1 1/8oz of #6 over a charge of C&H No 6(?) or 40-something grains of schultze.
We still don't know what the quick and dirty rule of thumb is/was for the vast majority of guns! I imagine it's just as much art as science, though.
RG
