Wow - look at the case hardening on that lockplate! But is that really a Whitworth barrel? What you can see inside the muzzle doesn't look like Whitworth rifling to me - it looks more like a Kerr (so-called ratchet rifling). Granted that the rifling could be worn some at the muzzle (although the gun looks practically unfired).
I wonder what period records substantiate the import of T. Turner rifles by the Confederacy ... anyone here seen any?