Odd about the sights, though.
I agree that they should have had protecting wings or something. The Mark III* which was made for England did have such. This would have shown up before the War, had there been rifles and time for a proper trial.
As to the battle sight, it was no worse than the battle sight on the US Springfield Model of 1903, which was set at 547 yards. At least, with the Ross, you had the option of using the aperture sight, which COULD be set for shorter ranges and works very well indeed when so set. The Ross Battle Aperture Sight as fitted to the Mark III has two scales: one in hundreds of yards (with intermediate markings, of course) and one in minutes of muzzle elevation. The drift-adjustable aperture, though, could be a little tighter, but this varies with age and wear and rust and dirt. It's hard, at this remove in time, to say what they were like when new., although I do suspect that they didn't creep about all by themselves.