I was shooting a couple of .22 pistols today down by my barn using the Aguilla Super Collibri rounds and not doing too bad. I had a piece of 3/8 inch CDX with plenty of knots for targets and was hitting about as good as I can shoot freehand. My wife was shooting her .22 S&W Kit Gun and doing well also. After she got tired of shooting and went back to the house to fix supper I decided to try the knots on some railroad tie blocks that I haven't split yet for firewood. This was a total head up ass thing to do, I'll admit. In hind sight it should have registered in my brain that those tugs at my pants legs were ricochets but not untill the hornet like sting in my left upper arm did I get a clue to stop. My fault totally. It didn't penetrate but whopped the hell out of my arm and raised a knot. The 3/8 inch plywood was leaned up against the barn wall and slowed the bullet down enough so that it was only hitting the wall and falling into the grass. The tie block just threw it right back at me.
Use a proper back stop when shooting these little rounds. Those little bastards hurt.