I shot 62.0 grains of TAC with various 225-grain bullets and 59.0 with 250-grain Partitions in two different .350's (Ruger 77 Mark II and Remington 700 Classic) and the velocities and accuracy were great in both.
With 200's there some other powders are as good in the .350, but with 225's and 250's TAC is about the best powder I've tested.
It's also about as good as it gets in that rare but fantastic wildcat on the .350 case, the 9.3mm Barsness-Sisk.
