Well, I'd say that given that they came from Russia, where guns were used hard and put away wet, repeatedly, all with corrosive ammo, I'd say the chances of you getting even a select one with a bright bore are pretty low.
Considering 99% of the Nagant's on the market are Russian refurbs your chances of getting one with a bad bore are very low. I have yet to see a refurbished Mosin rifle or Nagant revolver come from the importer with a bad bore. Whats the point of sending a gun through the refurbishment process if its going to come out with a crappy barrel? The only Russian refurbs I've seen with bad barrels are ones that were abused by their new owners here in the US. (shooting corrosive and not cleaning properly).