canoeguy,
I know I use W231/HP-38 for a lot of calibers but I'm telling you, it really does work well in the .38 S&W.

I would start with 2.2gr W231 under that 158gr bullet which should get you ~600 fps from a 4" barrel. I usually charge 2.5gr under a 160gr RNFP bullet.

__________________
Freedom is never free!!
SWCA #3437