I used to work with a guy who used a .223 to shoot varmints on his farm. One day he decided to see how much steel his .223 would penetrate. He propped up a steel plate against a saw horse, walked back about 50 yds and shot the steel plate while standing. The slug impacted the steel plate, and then a slug fragment bounced back and hit my friend in the abdomen and penetrated his liver. He had to have surgery to remove the fragment and spent a week in the hospital contemplating inelastic collisions.
Another video of a ricochet:
http://www.youtube.com/watch?v=fS4tcLg5oCg--shinbone
