So to you a little black paint to prevent rust when in transit no longer makes it original unissued condition?
Oh, is that what they did, then?
And you read this from which Soviet source material? Or was it the importer who painted them?
The point is that half-a-century is an awfully long time to spend in storage.
The numerous inspection/proof stamps are evidence that even stored guns were regularly removed from storage -- possibly, even likley, issued in to service. -- as gewher76 stated his father barely fired his issued rifle -- and were later placed back into storage. There is no way to say with certainty the any given rifle never left storage, or was never issued, or never underwent some extent of arsenal repair, tune up, or rebuild.
The closest anyone can get to making such a claim is a "high degree of certainty." Such a determination being reached using various yardstick attributes which are widely accepted as being co-incidental to original condition.
As I have already pointed out, your OP rifle fails in various areas of this type of objective examination.
It seems somewhat obvious that you are too emotionally attached to the claims you make, and the rifle you own (beautiful, yes. It is) to step back and see it OBJECTIVELY for what it is.
We've all been there.
Perhaps you need to let go and:
https://youtu.be/OWDOSnC9aCs