Wow that brings back memories. My Dad bought me a pellet gun (my mom wasn't impressed at all). I was mad at something so I took my piggy bank and was shooting at it. It ricocheted back at me and parted the hair in between the top of my ear and my head. Freaked the crap out of me, the Damn piggy bank was shooting back!!! I ran and put the piggy bank back in my room LOL.
A vertical back stop isn't a very safe thing to shoot projectiles at.
Ya, like others have said he is lucky it didn't hit hit in the face.
OUCH.......................