Everything I shoot is "jammed" .010" into the lands. Mostly BR rounds. 22,6,6.8 and my .221 Fireball.
Build your load with them jammed. Find the sweet spot with the best group. Then, back off and see if the accuracy changes. As a rule, larger calibers prefer a jump to the lands. And only change one thing at a time. Keep the same powder charge and adjust the seating depth.
Being that you're single loading, you don't have to be concerned with mag length. Throat length may be a factor. You don't want the bullets to be falling out of the case neck while trying to reach the lands.