I'd like to throw this in about the Mosin:
Regarding sights: These rifles (assuming the barrel is in good shape) are shooters and capable of shooting quite well to 1000 yards, using the proper ammo.
However, most are shot (in competition) at 100 or 200 yards in CMP GSM Vintage Rifle Games (Matches).
We know of course that the windage can be adjusted via the front sight. But the elevation on these rifles leave a lot to be desired, some shoot high, some shoot low. OK if they shoot low, you have the means of adjusting for elevation to get the point of impact where you want it. But if it shoots high at 100 yards, and you elevation is set on the lowest setting, then you got problems.
This can easily be fixed. A movement of .06 on either the rear or front sight moves the impact one inch at 100 yards (or MOA). If the gun shoots low, and you want it zeroed with the rear sight is set on zero, then simply take .06 off the front sight for each inch you need.
Its hard to add height to the front sight, but we can lower the rear sight.
Simply punch out the pin holding the rear sight leaf. Turn it over and you'll bind a base that rest on the rear sight fixture. Carefully grind it down (bottom side) .06 per inch you need to come down. Its better to use a milling machine so you can get it perfectly flat so it sets evenly on the base without wobble.
Now you should be good for 100 yards with the windage is set for 100 yards, allowing you to shoot any range you desire.
As far a windage, again thats adjusted by the front sight and is difficult to adjust in a match. At extended ranged you need to hold left or right. You need to learn the size of the front sight in reference to the target.
At the CMP GSM Vintage rifle matches you only shoot up to 200 yards, so wind isn't much of a factor unless its really blowing.
These guns are great for shooting a piece of history, once set up its done, now just work up the ammo that shoots best in your gun, they don't have to be loaded hot to get to 200 yards, I load 42 grns of 4895 pushing a Sierra 150 grn .311 bullet. Its easy on the gun and shooter. Its capable of 2 inches in my gun, which is more then accurate enough to clean the target used in the Vintage Rifle Matches.