Next question is how did it end up way down here? Lol.
Since you said it matches the rest of the gun, that carbine came across the border without passing through customs, likely in a shipment of personal items that wasn’t thoroughly checked. If this is the case there should be no importer stamp on this carbine. Russian SKS45s are not (legally) importable into the United States from any source since the implementation of the VRA in ‘94.