My shooting experience has been cowboy mounted shooting. I have learnt and become proficient with decocking my revolvers using only my strong hand and thumb to hold and lower the hammer, whilst my weak hand holds my horse's reins. I understand a method used in other action sports where both hands are available is to use the opposite hand thumb, rolled under the hammer, to lower the hammer. In your action sport is there a particular rule that states how a hammer must be decocked? If not a rule, is the thumb roll method preferred or if you can demonstrate proficiency, just do whatever works for you is ultimately acceptable?