Nothing happened, and nothing could have happened other than him missing a practice target by a mile. It doesn’t even show him aiming at something in particular, just looking down the barrel. Ammo can kill you, not having a working optic is not a safety issue no matter what direction it’s installed. Did he check the chamber to see if there was a round? Did he flag any other sailors? Did he keep his weapon pointed down range? Every single person around him let him shoot the weapon like that, they obviously didn’t feel too unsafe to be around him. None of them even seemed to noticed it was on backwards either. How can you tell it’s backwards from this picture of him?