You need to measure your barrel's freebore, and then begin by setting your OAL's at a given number. I usually start at setting my bullet jump at 20-thousands off of the lands. Then I will move closer and farther in increments of 5-thousands. It's rare that I put the bullet right up against the lands.

For a .223 (which I know your not shooting) I usually just set the OAL to the SAMI setting as I find fooling with the OAL doesn't do much on a .223. But....that's just me. Don't take that to the bank!!

Dave