Accuracy of MN's is highly variable and adding a scope isn't necessarily a good idea. I've got a decent shooting M39 Finn. Not great for a Finn, but it shoots better than 90% of Russian MN's. My buddy bought one of the $79 91/30's and refinished and scoped it. He was all stoked up to outshoot my other buddies $900 Bushmaster with a $79 surplus rifle. Anyway, I challenged him first with my M39 and iron sights and I smoked him. We fired 10 shots each at 100 yards and all ten of mine were in the black with about 8 of them in a 2" circle. Even with the scope his were in about a 5" group with none of them particularly grouped together.
I've got 4 other MN's in my safe. Only one of them is a decent shooter. My M44 will shoot about 2.5" groups with good ammo, (the bore on that one looks like new and the metalwork is excellent). I have a 91/30 hex receiver that shoots about 3.5" groups another that shoots maybe 6" groups and one that can't hit the side of a barn from inside. It literally shoots about 12" patterns at 10 yards.