As a shooter, I can’t imagine how that could happen. I could understand a recoil that would hurt a person nearby—but unless he were aiming the gun at himself I can’t see that happening.
It has happened at least once before with the big bore guns. Several years ago a woman was trying to shoot her boyfriends gun and she ended up shooting herself in the head. These guns recoil violently and some try to re-grip the gun as it jumps, and end up pulling the trigger again.
There are plenty of on line vids of folks (mostly women) losing control of 44 mags and such when shooting them.