Probably true. My work with 4166 peaked at 2779fps with the Speer 150gr Grand Slam but even 100fps over factory loadings is pretty meaningless. I think accuracy translates even worse between guns than velocity, would like to have tried the 2500fps A-MAX load in that 99R though.
The claimed temperature indifference and copper fouling removal of the new powders is interesting, I'll probably try CFE223 with the lighter bullets since that one works in other calibers for me. Part of the reason I buy different calibers, or something else in a caliber already owned, is to see what I can assemble for it.
