It could well be a true bringback, but it could also be a surplus rifle sold in the eighties for $80 that somehow slipped through without import marks. Either way I would figuew it to be worth more than a similar import marked import. In my humble opinion without the paperwork it should not be considered a veriable bring back (it may wel have been a genuine bringback with a hell of a story with it, but that doesn't really matter), as the documentation is what really gives these items value.
I broke a guys heart this week when he asked me to help him identify a couple of "war trophies" his great uncle had "brought home" from the Korean war. His uncles battlefield pickups were a pair of like new unissued condition in the cosmoline import marked pistols. One was a CZ52 the other was Norinco stamped import marked Tokarov. Nice guns, and probably worth $200-300 combined in thier pristine condition, but definately not the war trophies his family had been led to believe (unless the N Koreans and Chinese were using CAI as an arms supplier).