Well from what has been tested in the past, that a bullet fired straight up into the air when it falls back to earth the amount of energy the bullet has MIGHT cause a cut on your skin if it hit you directly. I know that Mythbusters did that as an experiment and found out the terminal velocity of a bullet, and shot those bullets out of an air cannon and they "stung" the persons hand received the "shot" Now I am not talking about something that goes downrange, but basically straight up. I am not condoning it, just stating that the damage that a round would do it negligible at best.
Gunner
We have removed bullets from the roof on both of our houses (next to each other) and both were deep enough to cause water leaks in the rain. May not have been "Straight" up but it would have went a lot deeper into a body than they did in the roof.
Please do not shoot your ****ing guns in the air. We may shoot back......