I used to shoot with a group in upstate NY. 12-15 met each Sunday in a heated building and shot at 50 and 100 yd targets thru a hole in an exterior door. One of the participants had a TC from its custom shop. We all swabbed between shots with a damp patch since we had plenty of time. This person chose to swab with a dry patch,and he had shot with us numerous times. Suddenly, I hear a Boom!, and turn to see this guy holding his right hand. He had swabbed, poured his powder in and was seating the patched round ball when it touched off. Blew his range rod thru the ceiling and halfway thru the metal roof of the building. The loading jag caight his fingers and ripped them open. Cleaned his hand before taking him to the hospital. Later I was told this happened again without injury, but he never shot again. We never could figure out why his rifle did this. I do not swab while shooting outdoors and have never had an issue, but I was present when it happened to this poor guy.