Chainfires come from the front. Had one. Didn't get hurt but it scared me. If the ball does not shave lead when loaded--fire can jump inside the next chambers. I don't remember if my bullets were exactly right diameter at the time (1974) but I have been told to always use a wad or grease. And I have also been told that if the ball shaves lead into a little ring it won't chain fire. I use wads anyway