That's the trick: fast burning powders. But no matter how you slice it, even a snubby .357 is going to out perform any .38Spl. They will out perform due to the sheer pressure increase. With snubbies, the trick is to develop that pressure quickly - i.e. fast burning powders.
My short barrel load is a Speer GDHP SB 135g (#4414), with 7.5g Unique (which is in compliance with Speer Manual #14). It's probably pushing a little over 1000fps with a 2.5" barrel. That's more punch than a .38 is going to deliver. This round has nightstand duty at my house; in a 686 w/ 4" barrel. I believe Speer makes this round as loaded "short barrel" ammunition. If you don't load, this would be the round I would recommend.
With a snubbie, going with a slower powder may - may - give you a few more fps, but it will come at the expense of a great deal more muzzle flash and noise. Just not worth it. Loading for short barrels requires an attitude of restraint; and understanding that the data in your manuals are almost always for longer barrels (Speer #14 has short barrel data - which is highly invaluable). You need to know which powders are faster than others, and "visualize" how those velocity figures will distort with less barrel length. With a short barrel, the velocity figures aren't going to reduce in a linear fashion. The faster powders will see less of a velocity penalty, and the slower ones more.
