Originally Posted By: pahntr760 OP, load a round with your intended bullet, measure the neck diameter, subtract .002" off that. This is the recommendation from Redding. It works for me.
This is what I do too
If you have a seater die, as Shane said, load a round and measure and subtract 2 thou and your good
If not, you can measure case wall thickness x 2 and add bullet diameter and subtract 2 thou as well, but the seated bullet is the preferred method by Redding