Deeangeo
In my opinion:
- Your rifle was proofed in Vienna ("NPV" is the marking of the Vienna proof house) in 1922; markings of the kind "1779.22" are Austrian, not British.
- It was subsequently imported in the UK; if imported from 1925 it should also bear the marking "Not English Made".
- After being imported it was also re-proofed in the UK in London, as shown by the British markings on your picture “GP” surmounted with a crown (this has been the London definitive proof since 1637), “V” surmounted with a crown (this was the London view mark until 1955), “GP” surmounted with a lion (the London provisional proof for barrels since 1813) and "NP” surmounted with a scimitar (this has been the London definitive nitro (smokeless) powder proof for all guns since 1904).
Regards.
Louis