I have a Springfield Trapdoor Carbine (I think) with Serial Number 1399**. I can tell the stock is an old replacement without cartouches. It has been questioned as to whether it is truly a Carbine. The stock is not cut down or "fixed" as it is all solid wood. I measured the OD of the barrel at the muzzle and it is nearly identical to the OD at the muzzle on my other, known rifle. I also measured the OD on my rifle at the approximate distance lengthwise of the "carbine" muzzle and the rifle barrel was larger. This seems to prove the barrel was not cut down. The "Carbine" barrel muzzle is crowned similar to the rifle. The websites I have found do not give the breakdown of Ser. #s between rifle and carbine. The best I can determine is it was made in the last quarter of 1880. Does anyone know of a source that can confirm if my Serial Numbered gun was originally made as a rifle or a carbine? Thanks for any help you can provide.