To get uniform and consistent neck interference, my final sizing on the neck is done in .0005" increments so I actually get about .0005"-0007", so I get .0015"-.0017" interference. If it's a rifle that requires .004" interference, which is rare for me, I adjust my mandrel in .0005" thicknesses until I get the .0005" springback required for final size. A few tenths over or under mean little, but they ALL need to be the same, any more than this get removed from the batch. All my brass is annealed to the same specs (read hardness) as factory brass.
Most of my rifles run just under .002" interference, and final measurement is always taken after springback the next day, not all brass stays stable over time, especially newer brass that is only 3x fired…
Cheers.