I've been loading 8-9 grains of unique under a 255 SWC for several years. I've tested 8-9 grains of power pistol under the same bullet. Velocities are very close (8.0 = 860, 9.0 = 950) with both loads. I'm thinking that when I use up this batch of Unique that I'll change over to Power Pistol simply because it gives me less variance when dispensed from my RCBS Uniflow.
All that is neccessary for evil to triumph is for good men to do nothing.