A cleaning rod into a pine tree at Ft. Huachucha. At least I had a Private's sense to stand back 20 feet. It sunk into the tree a good 4 inches.
BTW, I had a bullet whizz past me on a 50-yd mini range after it ricocheted, it left a lead trail on the concrete several inches from where I was lying. I'm still completely mystified how this could have happened. How could one of us have been so off-target when instructors were standing behind us and carefully watching what we did?