Start w/ the Full Length resizer die about a quarter's width (1.75 mm or 1 turn) off the shellholder Try to chamber a sized casing. (It may now have been side-squeezed/lengthened too long and the bolt will not close easily.) Gradually adjust the die down to where the case will just
re-enter the chamber and the bolt close w/o any significant feel. Lock the adjustment ring at that point.
That will size your case to custom fit the chamber (pretty much) as well as a neck sizer only.
Pick up Hornady comparator kit ...
...and you can turn what you've determined by feel -- into a measurable science.