A lot of guys are having issues with comparators. Measuring excessive shoulder bump to get the brass sized for a smooth bolt close. The main cause is a comparator that contacts at the shoulder/body or neck/shoulder junction. Dies reduce the diameter of the neck and body. When the comparator contacts at these areas you will measure that diameter reduction as shoulder setback, when no shoulder setback has actually happened. Spin the case in the comparator so it leaves a shiny ring on the case so you can see where its touching, you want it in the middle of the shoulder, if its at the shoulder/body or neck/shoulder junction and your having to bump the case more than .001-.002" this may be your issue. The little comparators that come with some dies are a big culprit.