All my qualification fire and practice before we transitioned to autoloaders was fired double action. I can share two things for double action competence: The revolver's action must be smooth for its entire travel, not necessarily light as the gun must fire every time. And, in his book, "Fast and Fancy Revolver Shooting," The late Ed McGivern said that the trigger must travel forward at the same speed it travels rearward. This was probably the single most valuable piece of information in his book. Once I grasped that concept, I proceeded to shoot perfect scores, right or left handed, and never went back to single action fire except for sighting in and accuracy testing.