+1 on what the others are posting,
reloading used .357mag cases is the way to go. I also reload to .38spec levels using 6.5gr Inique with 158gr Speer bullets and std. primers, with .357mag cases of course. This avoids the carbon buildup in your cylinder using plain .38spec ammo. I get an avg. of around 1050fps with my Ruger Blackhawk 6-1/2" barrel. About 900fps with my snub S&W.
Unique is a bit dirty and maybe not the best choice but it's what some friends and I got started with.
For full power I just use factory, Fed AmerEagle 158gr .357mag. It get close to 1500fps.
Oh, BTW, I'm sure you've checked the reloading forum, tons of data there, like this old thread on .357 reloads with some posts of mine....
Beware of some of the "experts" however, and just read lots of info to make your decision.