Plenty sadly. One with a machine gun fun shoot and someone let a kid shoot an smg and it walked back over his head and shot someone. Been around a few unintentional FA pistols when they had a failure. There is a reason you test unknown guns with one in the magazine only first.
I used to recommend two in the mag. With only one you can't tell if it's going to double tap or not, only that it won't blow up. Two is still nominally controllable. I can attest that an unintended full mag dump is a scary proposition. Every bullet has to come down somewhere.
Right or wrong, I diagnosed a Sterling hammerless .22 pistol as having slightly too much clearance between the firing pin and the channel in which it rode. This allowed the firing pin to slip off the sear with the impact of the slide closure. It could have been repaired with a new, "higher" sear, but I decided that was too much of a balancing act. I don't have it anymore, but I can't remember what I did with it. Probably a decent burial at sea. Well, OK, burial at lake, anyway.
Terry, 230RN