Perfect, just the info I was looking for.
I was hoping that there would be some load info engraved on the gun but unfortunately there is not. In fact, I would need to verify the actual cartridge as the 577/500 No.2 is a circumstantial guess. The gun has some brass with it and the brass will chamber but I would still do a cast to make sure...
I wish that the buy-in on English rifles was not so high!