What would be the current import status for "gunsmith built" Enfield target rifles - i.e. a rifle identical to an L39A1 in all components, but built on a random No4 receiver with original markings? Is there a specific date cut-off, i.e. would a 1945 Mk1 or a 1949 Mk2 be ok, but a 1954 PF- Mk2 not be ok?