Let me first say I do not own a revolver, nor do I have much experience with them.
I just read the article in the October Concealed Carry Magazine about how to de-cock a revolver. It went into great detail about how far to let the hammer drop prior to releasing the trigger to ensure the hammer did not strike the firing pin and accidently fire the weapon.
My question is why not just open the cylinder/wheel so there is zero chance of the firing pin hitting a “live” round? It just seems like it would be more fool-proof than risking a thumb slip while lowering the hammer on a live round. Then you could close the loaded wheel back into place.
Again, I do not own a revolver, or I would experiment with this myself. Maybe you can’t release a cocked hammer with the wheel open?