I have never used the 38/357 myself but I have loaded some for my friends.
They asked for UNIQUE and #9 shot.
I myself have loaded and shot many hundreds in 44 mag, 44/40 & 45 colt.
All were loaded with UNIQUE as that is what I had the most of using #8 shot.
Before speer had the 45 capsules I loaded with a gas check turned upside down with great results.
Just don't shoot them inside a building.
Don't care for flying gas checks, and they are a little hard on the walls of a metal building.
As stated by Savage, keep with the lower velocities for the best patterns.
You will find that they will print in a half moon shape at the longer distances, say 20' to 30'.
I do have an old 10" TC barrel in 44mag with the screw on choke that has virtually no rifling left that will print a nice 14" to 18" pattern at 20' to 25'.
This has taken many rats and a few squirrel.
LONGTOM