longbeard,

I always load my bullets at a length that a bullet blacken with soot will show land marks in the soot, but will not show a bright spot where the lands actually touched the bullet. Or, just touching the lands. I've proved to my own satisfaction to many times to count, that this is the point that usually gives the best accuracy. There have been a few times that this has not been the case, but not very many. Sometimes OAL is determined by length of rifle action or magazine.Or by location of cannelure on a bullet, such as for lever action rifles. I even go to the point of determining the actual length of a chambers neck length. Then I'll trim my case necks .005" short of the max length just to get as much neck length holding a bullet as I can.