Don't bet on it, The Russians refurbed there Mosin Nagants a couple of times between WW2 and the late 70's. An original Russian MN is a rare bird to find, the closet eamples to be found are Finn captures, or SCW rifles.
Amen to that.
Nothing wrong with refurbs, but collectors don't particularly care for them as they are not as originally manufactured.
Here's how to tell if you have a Soviet refurb (NOT how to tell if you have an original rifle). If any of this (in the link) is true - then you have a refurb. However.... determination of an original Mosin takes some serious expertise, as there are many other variables that may come into play.
How to Tell if Soviet M38s, M44s, and 91/30s are Non-Original Rifles
Les