Well anytime you change and aspect of your load, be that powder, sabot, bullet or even ignition.. there is a CHANCE in can change the POI but that is no guarantee it will. Besides, you're shooting a very high quality rifle able to handle powder and pressures very well. I really am not surprised that the POI did not change all that much. Sounds like a nice group. I shoot the same Buffalo Bullet 375 grain SSB with 100 grains of Pyrodex RS out of my Ultra Mag with amazing accuracy.