I believe I understand your question, and the answer is "no". Keep in mind though, that both the trigger safety and the grip safety must be engaged for the gun to fire.
Maybe I am missing something here but it seems the way I would uncock the gun is to remove the mag, eject the round, pull the trigger, and put the mag back in. My Nano does have a decocker button.
Okay, I guess I misunderstood your question. I thought you were asking if an XD could be uncocked with a round still chambered.
