Sounds like a No. 2. The standard length 28-gauge shell was 2 1/2 inches with a load of 1 3/4 dram equiv. and 5/8 ounce of shot. The extra length hull for the 28-gauge was 2 7/8 inch and even in his 1910 book Capt. Askins was writing of using the 2 7/8 inch shell in his 30-inch Parker Bros. 28-gauge, but it weighed 6 3/4 pounds!! While the ammo manufacturers didn't offer more then 5/8 of an ounce, the good Capt. was loading 3/4 of an ounce of shot in his 2 7/8 inch 28-gauge hulls. The early Parker Bros. 28-gauges were built on the 0-frame, the lightened 00-frame didn't come along until later. I have a 1915-vintage Flues No. 1S 28-gauge with 30-inch barrels and it weighs 5 pounds 1.8 ounces. Ithaca advertised Flues 28-gauges as light as 4 3/4 pounds. It is these light Flues smallbores where I have seen the most instances of cracked frames. Ithaca lengthened their standard 28-gauge chambers to 2 7/8 inches in the NID in 1932 when the Super-X 28-gauge shell came out in that length with 3/4 ounce of shot. According to the table in Walter's book 326,830 would be a 1920 gun.