If you get an American optic you might be able to at least see the target that far out but conventional battlefield doctrine puts the max effective engagement range for a battle rifle like that at about 400m. That's one reason why the Russian POSP optics only have a range finder for 400m max. If you can find a Russian optic, avoid Kalinka good optic crap price, and you have the original side rail a POSP will serve you well. I tried an American red dot and it wasn't a good fit. All the after market Weaver and Picatinny rails you can get seem to be mounted on the least stable parts of the weapon, like the gas block or the dust cover. The receiver mounted side rail seems to be the best option for consistent zeroes, unless you find it relaxing to bench shoot.