as a mosin user and one uses it to get new shooters into the fun, i have to say a mosin is very forgiving with what you stick in it, just keeping her clean will help with accuracy.
if your a traditionalist and like shooting the rifle as is i have a few points to make.
the mosin nagant is a good rifle, very dependable, but it can get heavy, and as they were intended as troop rifles, having it lay on sand bags or shooting while sitting is not out of the question. people were sitting in trees using these, and laying in dirt/snow ( thats how i typically shoot is lay down or sitting). standing i can be accurate, but my mosin is rather heavy due to its front bipod (look at my sig if your curious)
mainly the focus you need to worry about is getting consistent groups. try holding your breath and releasing it right before you pull the trigger, and dont be scared of the recoil as my dad would say. lean into it while standing or sitting , give good leg brace points, and fire. the more stable you are when shooting the better the groups
@slamfire, your shots are rather wide spread, i can only ever get good groups with TAP hornady rounds, anything else it spits out into wide groups. but with that on a soccom m1a im shooting 300 through the same hole . just a suggestion to try that bullet, or the seirra matchking. you also may want to swap the piston, and spring guide rod, that really improved my groups.