i use the blackened bullet method.... kinda... i use a neck sized case and when i size it i just barely get it to the point where it will hold the bullet securely, but i can still move it easily with my fingers... before i bother blackening it (or you can use a black sharpie, its easier) i just barley seat the bullet in the case with my fingers and chamber it slowly... letting the rifling seat it the rest of the way... pull it out and measure, repeat a few times to make sure you get the same results... then do it again a couple of times with the bullet blackened... if you are getting the bullet jammed into the lands and it sticks in there when you eject the brass you have the neck sized too much, try it again with a different case.. this will give you the distance from the base of your brass to the start of the rifling... don't forget to back off a bit especially if you are near max loads
