I don't see how there could be any benefit to a dimpled ball in a revolver. When the bullet is pushed into the chamber, the sides will be wiped of any dimples.
I suppose if all you had were slightly undersize balls, dimpling could bump them up enough to "stick" in the chambers under recoil. But with a properly-sized mold to start with, I don't see a benefit to dimpling the ball.
Now dimpling can be used to obliterate the sprue, and maybe there is a benefit to that.