Is it possible that a mag primer might help with max and slightly over max load data? A slightly larger flash hole to bring that mag primer fire to the powder maybe? Just some random thoughts since i normally shoot milder primers and have poor results with max loads in general.
How did sabots look from the different loads? The Harvester smooth green is pretty strong but did you get a chance to compare them?
The lower velocity is just kind of strange considering some guys get good results with that much powder and a 200gr in a 40x50. I havent but....