After sleeping on my results, further considering my forehand grip (recalling increased down pressure) on the 0.070" flier, re-reading the PRB info, measuring extreme spread and extrapolating Average Distance to Center (ATC) of groups; I've concluded that I likely have identified for this rifle : bullet combo, two 0.009" wide seating depth accuracy nodes at jumps from 0.056" to 0.064" and 0.070" to 0.078". The longer jump possibly being the most accurate of the two.
Where am I missing the crux of this method?