Muzzle-loaders, partial rearmament, and torpedoes

Shannon entered service with two ten-inch and seven nine-inch muzzle-loading rifles, weapons that already imposed serious ammunition and training burdens. The 1881 work replaced only part of that battery with six twenty-pounder breech-loaders and also added four torpedo tubes. Some positions retained older weapons or remained unfilled, so the refit did not create a uniform modern armament. The mixed fit shows the limits of trying to update an already unsatisfactory hull during a period of rapid weapons change.