It's a Steyr-made Norwegian Krag that somehow got to Britain, where it had to be proofed.  So, it has a lot of British marks.  .256 was the designation the British used for 6.5mm.  So it's 6.5 Krag aka 6.5x55.  Westley Richards was very famous British gunmaker. They may even have some records that will give you more info.    (You need to Login; I have read that the Norwegians consider the later Steyr receivers as the strongest.  1897 was the last year Steyr made them.