Do yourself a favor and get a set of Redding Competition shell-holders and forget most of what you think you know about measuring shoulder bump. Cranking in a die an eighth of a turn at a time might seem precise but it is 1 divided by 14 divided eight, or with the tiniest bit of rounding .009" at a time. Factor in that the die is up flapping in the breeze and at the mercy press flex and brass hardness so you are measuring with micrometer and cutting with chainsaw. Heck, you're cutting a moving target with a chainsaw.
