I know what you are talking about david, I was at a re-enactment in 1989 when one of the re-enactor (union) was shot. It turned out that the man was hit in the leg by the Skirt of a minie ball that had been poorly casted. The skirt had seperated from the bullet and become lodged in the Barrel after the man had been out hunting with that weapon. Because the skirt was hollow the Safety Inspection had missed the foriegn object in the barrel. Naturally the Skirt came loose midway during the re-enactment and flew across the Battlefield about 100 yards before stricking the Union Re-enactor in the leg and leaving a perfect round ring bruse.