My standard powder I use is win 231/Hodgdon HP38, not loaded real hot. I got some AutoComp by winchester some time back, which is a little better suited for the 40 then 231 is, but never got to shoot off the rounds I loaded yet. Silhouette from Ramshot is supposed to be another good one for the higher pressure rounds, its basically the same as the old WAP, just with flash suppressant.