I have no idea, suppose it could be? It's actually a C No 4 Mk I*, # 9219330. It is odd as it has a rear sight marked "B" with elevation only to 800 yards. Been told that was a No 5 rear sight?
My Ross still has it's 30" barrel. I've a pleasant load of IMR 4895 pushing a 150 gr Hornady .312 SP along at 2950 fps. The Ross M10 with it's multiple front lugs is quite capable of increased loading as is the P14. Should be as effective on deer as any 150 gr 30-06 load.
Of course, those loads should not be used in SMLE or N0 4 rifles. In the case of my M10 the cases are NS'd and will not chamber in the No 4. The cartridge boxes are also clearly marked for which rifle. I do not have any such loaded cartridges around anyway as I really don't intend on hunting with the Ross. It was just an exercise to see what the 303 would/could do safely in the stronger Ross action.