Full length sizing rimmed cases can definitely over work the brass. Compare a sized case to a fired case and see .My .30/30 load for many years has been a Lyman 31141 (from before they standardized on a 6 digit number) and 15 grains of SR4759 (I've recently changed to AA5744 because of availability) Now that all your range brass has been resized, you may be able to avoid full length resizing if you're only shooting it out of that one lever gun. Full length resizing is supposedly harder on brass than neck sizing but I've never tested the theory.
The problem with the 30/30 and other rimed cases is not the shoulder area but the neck/lead/throat can be "tight/short"
no longer own a 30/30 but when it was around we only used the lee whackOround loader. Never a problem.