I read one time that powder can get "smeared" on the wall of the chamber when you seat the ball, thus causing a "fuse" type of situation. This supposedly happens when a person gets sloppy when loading the chamber. The cure was a funnel of sorts, made out of a center fire empty cartridge. Using the funnel and topping the powder with a wad, and topping the ball with your favorite lube, is supposed to reduce your chances of a chain fire to ..... well, close to zero. So that's what I've been doing, plus it was a fun and easy project.
