Into the US, there would be no import duties as it is an "antique" not a "firearm". No FFL is required. Figure that the insurance and shipping ought to not exceed $2-300, IMO. This is my understanding from reading the federal firearms handbook issued to all FFL holders. I happen to have a C&R, myself, and imported a W.W. Greener Mauser .318 WR that was much younger than the old double rifle. It was c. 1939 so this is even older and therefore has even fewer restrictions.