I've got one of these in 500 No2 but mine has an ovate barrel with Metford rifling. Looks as though you could have any rifling system you wanted. They do have a look that only a mother could love but mine has really grown on me over the years. Great fun to hunt with and the No 2 really dishes it out the the pigs.
Was out hunting with it once and had walked quite a distance when decided to have a sit and look. The rifle had been carried using a sling and when I sat down I noticed that the nut the should be on the left hand side of the hammer pivot bolt had worked it way loose and was now somewhere between me and the car. Boy was I pissed off to have lost the little nut. When I finally got back to the car and cleaned out my pockets of cartridges and such I found that when the nut had fallen off it had fell straight into by back pocket and was saved. Some sort of practical joke had been played on me by the rifle I thought but it is now retained by a small amount of Loctite.