I’ll wager he got hit by the case, not the projectile.
Simple physics. The bullet weighs more than the case. Outside of a firearm, the bullet goes a little way, the lighter case goes a long way.
BTW, we used to do all kinds of stupid stuff with .22 ammo. Nobody got seriously hurt.
I think the claw end of the hammer snapped back and that’s what hit him.
Ding ding ding we have a winner!
EricT was the first after 50 some odd responses to opine that the bullet went no-where!
It was the brass casing that probably flew somewhere.
Keep the goober away from electric outlets, as has already been advised........