Exporting registered long guns from Canada to most States in the U.S.A.is not a problem,regardless of date of manufacture.The proceedure is as follows:
The purchaser in the U.S.A.retains a licenced dealer to act as his agent. The dealer then applies to A.F.T.for a permit to import the gun into the U.S.A. This permit may take upto 6 weeks to obtain. On the Canadian side,no export permit is required for transfers to the U.S.A [ie: but may be required for some other countries].
Once the seller is in possession of the U.S.A.export permit, the gun can be mailed by Canada post to the U.S.A. The export permit must be attached to the exterior of the package. The Canadian seller must then provide the Canadian Firearms Centre with evidence that the gun has been permanently exported.On receipt of same the gun will be removed from the Canadian licence holders records.
Cross border shipments of guns that will chamber current ammunition, "regardless of date of manufacture", is is a problem! Canadian regulations require pre-registration of all such guns![ ie;.410,28,20,16,12,10G.and all current rifle calibres.]
Obsolete sizes such as 32,8,&4,G; pinfire,obsolete rimfires and all antique muzzle loading guns, rifles and pistols do not require registration in Canada.
Canadian firearms regulations allow for cross border shipments for repair etc; Suggest you contact the Canadian Firearms centre for advice. As an alternative Canadian gunmakers Nick Mackinson or Les Paul may be be prepared to offer advice as they are familiar with current proceedures.