I think what you need is a good friend, or even a decent acquaintance who lives near the rifle and who can do even a 10 minute inspection of it. Buy him a bottle of wine or a case of good beer for his trouble, and one day, maybe the favor can be reversed.
I had this situation once on a very expensive rifle - pretty far out of my league, but I had a guy in Amsterdam where the rifle was supposed to be. So, why not ask Frans to take a peek at it.
Turned out the rifle didn't even exist - at least not in Amsterdam. It was a total fraud. The real rifle was in a safe in upstate Connecticut or something like that.