And any marksman worth his salt should be able to hit center of mass on a human at 500yds with IRON SIGHTS. The Marines have to do it at 500 METERS as part of their marksmanship qual. The US Army does it at 300m. And that is with an M16 and a 62gr 5.56mm green tip round.
As I said before, I am no fan of the Mosin-Nagant but they are as accurate as most military rifles of the same time.
The Finns re-barreled a lot of them and they were known to be unusually accurate. The Russians also used them very successfully in international competition. I suspect they were both selected for quality nad rebuilt for accuracy. Still the basic action is capable of extrreme accuracy.
The same can be said for the Springfield O3 or 03A3 or the Mauser etc.
Not my cup of tea because they are heavy and rough but they are a bargain.