I took all the careful precautions that my Dad had drilled into my head. Kept my finger off the trigger, was sure of my backstop, made sure my Sister was behind me, etc...
It took careful aim at the post holding up the laundry line, held a half-breath, squeezed the trigger, and dang it if that BB didn't ricochet directly back at me and tagged my Sister right between the eye brows above her sunglasses.
To this day my parents probably still don't believe me that I didn't shoot her dead on like a William Tell gone wrong.
With the Gods as my witness, the above is true.
Once my 15yo and I were shooting our AR-15's. A round hit the steel target holder and bounched back striking him in the arm. So, much energy was expended that the bullet didn't break the skin. However, it really burned his skin.