Thank you for the post to remind everyone to be fully diligent about all safety procedures regarding firearms. Glad your injury isn't more serious. I had a negligent discharge about twenty years ago.
I had finished an indoor .22 rifle 'milk bottle cap' shooting match and was in the clubhouse packing my rifle. The last event of the match is the only one where more than one round is loaded in the rifle. We shot a five round rapid fire group. I had loaded my last five rounds of ammo from my bench-block into the magazine and then fired all five during the match, so I KNEW my rifle was empty. I capped the scope, pulled the magazine out, opened the bolt, looked at the chamber, put the magazine back in and then closed the bolt while holding the trigger to release tension on the firing pin. BANG! a divot in the concrete floor just in front of my left foot. I felt like a complete moron. Thank God I had the muzzle aimed at the floor, as there were ten other shooters still in the clublhouse. I looked at the empty casing when I ejected it, it was the ammo I use for plinking, not the RWS Target I used in the match. Apparently there had been one round stuck on the mag follower that I didn't see when I loaded my five rounds for the last round of the match. I took a lot a razzing about the ND, but did get praised for having the muzzle pointed in a safe direction.