If your Champion is pre-1940 with a "two-piece" firing pin, do not dry-fire it. You will break the firing pin. Use a snap cap or a spent shell.
The Iver Johnson Champion is a quintessential American single-shot shotgun. Produced from 1909 to 1956 (and again briefly in the 1970s), it was the working-class hero of the field—affordable, reliable, and carried by countless hunters, trappers, and farmers. Unlike the elegant European break-actions, the Champion is a study in utilitarian simplicity. Its nickname, "The Farmer’s Friend," came from its ability to live behind a barn door for decades and still fire when a fox was in the henhouse. If your Champion is pre-1940 with a "two-piece"
You will feel a solid thunk . The entire barrel assembly will slide forward off the receiver about an inch. Lift it up and away. Congratulations: you now have a two-piece shotgun. Flip the receiver over. You’ll see a flat metal plate held by one or two small screws. Remove these. The entire trigger plate—containing the trigger, hammer, sear, and mainspring—will now lift out as a single cassette. The Iver Johnson Champion is a quintessential American