Several months ago I was shooting out in the desert with a friend. There was this old, really heavy industrial-looking fire extinguisher out there (already empty and shot-up). When I stood it up and shot it with my 9mm's they just dented it, but the 158gr .357 Magnums penetrated easily (through both sides). My friend shot it a few times with an AK-47 and it tipped over with the bottom plate facing towards us. I shot at this new, smaller target and my round hit right on the edge of the sidewall. We were probably about 25 yards or so back, but I took a piece of something in my left forearm. It's still in there and I can feel the lump pretty deep under the tissue. The entry wound was small, about the same diameter as the top of a push-button pen is. It doesn't really bother me until it gets cold out and then it gets kind of sore. I should probably get some x-rays taken or something, but I don't have insurance right now and like I said, it doesn't really hurt.
When that happened, I think the bullet ricocheted back and down into the dirt towards me because I caught some light spray in the face too. I was very glad I was wearing safety glasses or I might have suffered more damage. I'm sure glad that chunk-of-whatever-stuck-in-my-arm didn't hit me in the face or nuts and I'm glad it hit me instead of my friend. He wasn't wearing safety glasses, even though I had offered him my spare set.
My plinking is now limited to soda cans, plastic bottles and expended shotgun shells, but I still realize the dangers and try to set things up in as safe a manner as possible.