Why doesn't anyone ever mention Longshot? If you want to load some actual +P then load it. Sometimes I get this feeling from new guys that they are affraid they will get judged for wanting to load full house stuff. It's just not like that. We all have different hand loading personalities one could say, some of us like high velocity, some middle of the road, some super low velocity comfortable to shoot loads, and the list goes on as does the type of load to choose from.
Now, if your wanting a real live +P load you'll love this one. I personally load and shoot this one and it is quite close to what you might experience from a .357 middle of the road load. I've also chronographed it and velocities are in the same neighborhood as listed.
Both of these loads are straight out og Hogdon's reloader's pages.
110 grain Hornady XTP with 7.6 grains of Longshot = 1337 fps.
125 grain Hornady XTP with 7.0 grains of Longshot = 1228 fps.
If you visit the Hogdon reloader site you'll see a good number of loads for +P and standard 38 spcl..