After 4 summers of shooting .22s at paper and steel over 200k rounds we finally had a ricochet. The 22 popped back and hit an adult shooter in his leg (weird prone position, his bent leg was up in the air??? and it was hit). The bullet had a slight deformation on its nose and failed to break the skin (all shooters were wearing eye protection) had the shooter been wearing long pants he might not have even noticed. I can not remember where but I found in print a a recommendation of 60' for steel and .22s.
I had my day too, while running a pellet rifle shoot using paper targets inside a building for firearms safety I was struck above one eye by a pellet fired 180 degrees away from me. Right above the eye protection I had a beautiful perfectly round circle .177 cal. hole that shortly started to drip blood. The perfectly formed pellet was on the floor. Two of us, both with long experience, were paying attention. We never did figure out how it happened- even if you can't see him. Murphy is there. Eye protection is good.