I use the versatile full length sizer die, it will neck size, partial neck size, size the neck and partially size the body, it will size the case with control as in neck size, size the case and place the shoulder where I want it from full length to minimum length, to go-gage chamber to no-go length, to infinity or a more practical .014 longer than a minimum length case and that would be the same length as a field reject gage, and all the sizes in between in thousands, the difference? my dies work with the companion tool to the press, the feeler gage.
I measure before and after, again I collect datums, I have small base dies , Bar dies and the versatile FL dies, when measuring the difference between all three die I have to get the good stuff out to measure.
Body sizing only, when the body is sized only the body/sides of the case is reduced in diameter, when the body of the case is sized the shoulder of the case is forced out meaning the case gets longer from the head of the case to the shoulder, but who measures?
With a full length sizer die I size cases that are from .012 thousands shorter than a minim length case to a practical .016 thousands longer than the minimum length store bought, over the counter, commercial case, that is 28 different lengths, when checking a chamber the different length cases measure chambers that are from .012 short to beyond field reject, for a 30/06 chamber that would be .014 thousands.
Brass stretch and or flow, when sizing where does the brass go, Most claim brass stretches, any day now I expect someone to find skid marks on the case body, seems like it would be a good way to determine the number of times the case was fired, they still trim but can not find skid marks.
A friend acquired 30,000 plus test fired cases with the small round cup dent on the side, after firing the round dent did not move, it got hammered but it did not move progressively toward the mouth of the case.
F. Guffey