Frankenspencer?

[Selair]

Hey gang,
Came into this oddball of a spencer "carbine" which is confusing for me to say the least. The fellow I purchased it from received it in this condition. He suspected it was a shortened long rifle. The patent date stamp is 1860, serial 1221. There are vice clamp marks on the receiver and barrel, suggesting it was rebarreled at some point, however the matching serial 1221 appears underneath the barrel ahead of the forend screw. There are no other markings anywhere on the barrel. Six groove rifling. There is no saddle ring and no provision for one on the receiver or buttstock. There is a serial 688 (or 889) on the buttplate and buttstock. The barrel is 18 and 7/8" long and looks to have been recrowned at the very least. All the metal was reblued at some point recently I would suspect. Anyone care to take a guess at what I have here?

[Jim W]

Close ups of the barrel crown and front sight?

It's not surprising the barrel serial would match if it was cut down, since it would be the same barrel.

[Arizona Trooper]

Can't tell from the pictures if it's a 52 or 50 cal. model. The receiver is definitely a rifle.