I've only had 1 ND/AD in 30 years of handling firearms and to this day I can't tell you what happened. I had a Series 70 Colt Combat Commander that I kept in my truck. I was sitting in the truck, dropped the mag, reinserted it and slammed it home and BOOM!. I was so shocked at what just happened it took me a minute to get my wits about me and secure that weapon. Only thing I can figure is I has the slide safety disengaged and apparently my finger in the trigger guard.
I carry a Kimber Ultra Carry today because I still love the 1911 platform.