I have a reloading idea that I want to try and thought I'd bounce it off you. We all know that barrels vibrate and have sweet spots that need to be identified right..? My theroy is that changing the pressure spike with seating depth will vibrate it more or less violently producing bigger or smaller overall groups. Magnitude can only be identifed with many dissimilar loads to produce and average pattern. I have noticed in my light sporter Sako that my POI moves around the target as velocities change and that it might be fair to say using all the different positions may identify where the barrel is centered and not flexing one way or another...? So, what if you load 10 rounds or so of differnt charges and the same COL off the lands and shoot them all in one group while identifing or overlaying targets to find the center, adjusting for velocity as you go? Would need a little math to correct the velocities as 2800fps does not print the same as 3000fps but, it could b figured out. You could do this several times at different seating depths and pick the smallest overall group for COL and then charges/velocities that most frequent the center of all the groups? 40-50 rounds later you have a nice map of your rifle. Using the smallest group and most on centered load...it might just work? Hope you understand what I'm saying.