Would a bulky powder like TrailBoss be a suitable substitute for relatively fast-burning powders like Unique or Bullseye in a .38 Special case?? I don't know if the case is even big enough to get equivalent velocities nor do I have any idea what the accuracy potential of TrailBoss is (I shoot Bullseye matches and the best accuracy I can muster from my reloads is always a goal).
The biggest reason I have for considering a powder like TrailBoss is that it would seem to be almost impossible to double-load a .38 Special case with it.