The 3-inch 12-gauge Super-X load in the 1920s, when most Super-Fox guns were built, was 1 3/8 ounces of shot. The 3-inch magnum 12-gauge load with 1 5/8 ounces of shot was introduced with the Winchester Model 12 heavy Duck gun circa 1935. My 1928-vintage Super-fox handles both of those loads very well, but the time I shot a few patterns with the later day 1 7/8 ounce 3-inch magnums I got holes I could throw a small Brittany through.