OK. Let's assume all hell breaks loose for whatever reason. It's Virginia Tech, Columbine, and Ft Hood all rolled into one. You had no earthly idea it was coming. You've got a semi-automatic pistol with no round in the chamber. Hit the pavement!! That will probably be instinctive, but if you feel the need to practice, do so. Stay away from walls. Ricocheting bullets follow walls. Just trust me on that. While you are on the ground, assuming that you have been wounded in one arm, grab your pistol with your free hand, brace the butt against the ground and rack the slide back with all your strength. With God on your side, carry on.