I do believe you have nailed it. The chamber does indeed appear to be 14 ga. The rear measures .780" and front .765" . It also appears to me that the barrel was originally on a Muzzleloader, not only is the bottom of the muzzle shaped to accommodate a ramrod, but the breech has a small piece of steel silver soldered in to cover was I think was the flash pan. The majority of the barrel is twist while the lower portion on both side near the breech is plain steel. Now where to find 14 ga cases? Thank you both for your input.
Steve