If I tooks right...It probably is right chap. The thing is that the charge weight alone can hugely change the harmonics. On my old Dolphin (remember the green piece of Mecano?) it was almost precisely 0.6gr between nodes. The group used to tighten up around those weights.
Russell Simmonds proved a point be seating the bullet deeply (about 50 thou deeper) and it shot the same. It often depends how twangy the barrel is to start with I guess
People often get tied in knots trying to wring the nth degree of group size out of a load, manage it once when the stars were aligned, and burn a barrel out trying to defy physics, when they may do better settling on a stable and predictable load and burn a barrel out practicing positional or wind reading.