RL 22 was the most accurate for me using 165 gr. bullets. RL22 is still doing as good as any of the others using 180gr. bullets, but I think there is a velocity reduction using the heavier bullets with it. Retumbo and RL25 seem to be the best all around powder with 180 gr. bullets. I have tried all the ones listed above plus IMR 7828 and H-1000. H-1000 is the most accurate powder in my .300 WIN mag, but it is not as good in the ultra. Hope this saves you a few bucks and several shots!