The 120-123 class won’t group what is going on

[grayfox]

Bullet seating depth changes vary the MV only a little, assuming you’re not highly compressed. Seating depth affects exit timing the most (in relation to the pressure wave up and down the barrel). That’s why I vary charge first (over a chrony) then look at seating depth. Besides, in an AR you have more wiggle with delta-powder than you do with delta-Oal. Seating depth is more of a fine tune.