I guess it's a N.D.
I had put the rifles away and transitioned to a 1911. Pulled the hand gun out of the case, loaded up a mag, inserted it, did a slingshot rack to charge the gun. Had my booger hook off the trigger and after the slingshot to charge it, she went off. Chambered the round and fired it in one smooth motion. That'll wake you up.

That's never happened before. Thankfully other than my son, no one else was around to witness that. Put a hole in the dirt a few feet in front of my foot.
Fired 200 rounds without further incident but I sure was aware of where the muzzle was pointing when doing a slingshot or dropping the slide stop.
Got the gun home and did a did a detail strip of the slide, firing pin etc. Nothing jumped out at me and it only happened once but it was the very first round. That kind of took the fun out of the range session.

I was shooting some cheap aluminum cased ammo. Doubt that was the cause. What do you guys think, sticky firing pin maybe?