I have witness 2 NDs, in my time in the military, one was in Iraq, just coming off a mission we were entering a base, we approached the clearing barrels (just inside the gate of every base overseas SOP is to stop and clear your weapons) i finished clearing my M4 and M9, i looked behind me to make sure my team was mounting back up, as i turn to look i saw a Major that had never been on mission before not very field savy, point his Berreta 9mm at the clearing barrel, pulled the trigger and POP, ND, he then pulled the slide back, pulled the trigger again and POP, 2nd ND i then yelled over at him and said, SIR DROP YOUR F**KING MAGAZINE.
The second occured in Afghgan, a young gunner had a malfuntion on his M249while out on mission, it was a double feed, not uncommon for a DIRTY M249, when we RTB, he attempted to clear the chamber while still in the turret of the HMMWV, he had the weapons muzzle on the floorboard of the vehicle and after several attempts of yanking back on the charging handle as hard as he could, (NOT THE WAY TO CLEAR A DOUBLE FEED ON A MG) the charging handle released, ejecting one round and when the charging handle slammed forward it chambered the second round and fired through the floorboard of the vehicle, striking a brake line before impacting in the dirt. Needless to say both of these instances could have been avoided with proper firearms training, weapons familiarity, and some common sense.
As far as a ND while Dry firing, ive never seen or heard about that, its not a dry fire if the weapon is loaded, Basically the first rule of firearms around the globe, check, double check, triple check a weapons chamber before handling the firearm..