Yeh...the sight calibrations on most mil-surps may have once been calibrated to a specific cartridge loading....not so reliable in modern times. However good repeatable settings are still an asset if you have a notebook and pencil and shoot the rifle enough to develop reliable data.....my father called it 'dope'...which has an entirely different meaning in todays world.

Then again some ladder sights calibrations have never had much relevance to actual distance(meters/yards) and are there simply for reference to actual shooting discipline. An example being the old Winchester lever action standard carbine sights calibrated to 2000 somethings. This same sight could be found on anything from an M1873 .32-20 carbine to a M1894 .30-30 or M1886 in .45-90 and everything in between carbine-wise. A notebook and pencil plus some shooting are your friend.