Jato,
Was this at a shooting range? Can you explain the circumstances? I'm guessing this didn't happen because it jumped out of his hand while firing.
It seems the hammer would have to be positioned over a live round for it to discharge when dropped. If he had just fired, the hammer would still be positioned over the just fired empty case.
The NAA Mini seems pretty safe to me (even if dropped) because the hammer should never be over a live round until you're ready to fire it. At all other times it should be in one of the "halfway notches" between the chambers or over an unloaded chamber.
Apparently, some older NAA Minis didn't have this "safety cylinder" but they will provide one free to anyone with one of these older models.
I suppose one would have to be careful not to drop it while cocking the hammer etc.
Anyone else have any NAA Mini AD/ND stories to tell?