After I have done ladders with powder/s and seating depth's I then go back and retweak the best node in smaller powder increments and at that time I try checking a few to several different primers. Sometime I get a little lazy and forget about primers and just go with what has worked for me in the past but this target kind of reminded me that I shouldn't skip this test. Top row BR4's bottom row Wolf SRM primers. Same seating depth's and powder charges, same morning, same conditions, shot alternating BR4 to Wolf, wolf to Br4, etc.