Start by setting your starting point about 0.020" off the lands, and then set it in small steps of 0.005". Keep an eye on how the group size changes along with the vertical spread. You'll really want to pay attention to these details as you adjustI just finished a load workup for .308 using Lapua brass and Varget powder. Managed to achieve a great group at 100 yards, but I'm still tweaking the seating depth. What are you guys using for your .308 loads?