Back the die off? If I am neck sizing the case I adjust the die down to neck size. If I do not want the die body to touch the case body I adjust the die off the shell holder with shims. I could use a wild guestimate of 1 turn, one turn would be .071", meaning I would have a neck with .071" unseized.
Not my intention to put you on one of those trips. MY dies and presses have threads, most of my dies and presses have 14 threads per inch, simple math says 1/14th of an inch (1 turn) is .071". To make it more simple I use a feeler gage to adjust the die off the shell holder when necessary, I could use a dial caliper of height gage.
If I adjusted the die down to the shell holder then backed it off 1 turn I should have a gap of .071". From the beginning the answer has always been: "WHY make wild guestimates when adjusting the die when adjusting the die with a feeler gage is faster?".
Neck sizing with a 308 W full length sizing die: This is the part that drives most reloaders to the curb. I determine the difference in length from the shoulder/neck juncture of the 308 W case then do the same for the 30/06 case. I use that amount to adjust the 308 W die off the shell holder then neck size the case. I could add .010" to the gap to compensate for error or JIC.
F. Guffey