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.
The model M/28-30 is a little different from the later M/39 and the reworked Finnish models that preceeded it in that it mounts a heavy barrel with a .3085 bore rather than the more usual .310-.312 bore diameter of most Finnish and Soviet Mosin-Nagants in the 7,62x54 rimmed M1891 cartridge chambering. At the time, this allowed the use of the then-new 172-175-grain boattail bullets of .308 diameter developed by the Swiss for their M1911 and K31 straight-pull rifles. The bullet was also adopted for match loadings for the American M1903A2 Springfield rifle, and that experience caused the first U.S. match bullet loads for the '03 to be produced with a 172-graid bullet.
There are several other bullets that have come along over the intervening 80 years that perform as well or a little better than the old Finnish 7,62x53mmR loadings. Nevertheless, my three M/28-30 rifles can still keep all their rounds on a silhouette target at a half-mile, 880 yards, just as they did *back then.* And that's with iron sights and my 60-year-old-plus eyes.