I perform a 200 yard ladder test with my Bullets on a light jamb, my ladder is one charge in .2 gr increments as my bullet impacts climb the target I can normally identify a flat spot before I reach any pressure signs. I select a charge in between those two.
now onto the 300 yard seating test I fire three shots each of my chosen powder charge,starting at my jamb or -0- increase.005 each set of three shots. I'm not necessarily looking for the smallest group rather the flattest set of three. I now have my initial ( course) or base load. At this point I can test primers side by side to determine if any improvements appear I will note for reference or perhaps make a change. Now I can fine tune my seating to identify how wide my seating window is. Once I have that I can fine tune my powder .1gr at a time preferably at my intended distance " I my case I test at 550 yards as that is the longest range available unless competing.
example- my 6br load
Varget 30.1 gr
Lapua brass
cci br primers
SMK 107 gr bthp
seating .016 jump
results 3 shots under 1 inch at 550