what are your velocities and extreme spreads?

i shot a lot of 7828 in a 260rem and the best groups i could get were about what you have here minus the flyer...also 7828 is not the best powder for a 243 and i doubt your going to get much better out of it than what you have even if you get the flyer to shoot in the group...as said above the flyer can be caused by several things but id start by switching powers if it were me...i know its hard to find but H4350 would be my first choice..next would be H4831sc then RL-17 IMR4451 or IMR4350.