I admit to two accidental discharges.
One was on the range. We were trained to pull the trigger on our 1911 prior to releasing the slide. This was to maintain the same trigger pull. When I released the slide I removed tension on the trigger. The impact of the slide going into battery caused me to discharge the pistol. Shot the bench and cost me 10 points for a 90 score on that stage and the match.
Second one involved failure to check that a revolver was empty. A 38 wadcutter will not penetrate a good pair of leather boots. It does sting a bit.
Skitter Skelton wrote a marvelous book on misses. It involved accidental discharges and shooting full length mirrors while practicing quick draws in front of his mothers full length mirror. He admitted to shooting two mirrors.
If anyone can find the book I would love to get a copy. Someone borrowed mine and I never got it back.