“It's funny to see that happen at a match. Even with load and make ready commands , I've seen folks start to 'shoot' with an empty gun.”
I was invited to shoot an IDPA practice match once. My trusty 92fs and a new leather holster, man what fun. After getting around the ribbing I got for having a Beretta (instead of a Glock) I did great on the first scenario. When I ran the fourth scenario out of five, I did exactly that. “Go” and… click. The guy with the timer offered to let me have a do-over, but I felt that was cheating, and decided to live with my score on that one. I began to fall apart due to nerves after the second round, and got progressively worse on each round. It was a blast, and everyone there was great. I need to go do that again.
This thread is a good argument for having extra magazines in the glove box of every vehicle. It would have solved your problem, and would be a great back up on the days you don’t forget the first mag.