First hand experience, a client brought in Purdey double rifle with 2 sets of barrels that he was going to buy. Handsome and interesting self-opening rifle with a Jones UL. The Purdey address was upside down on one set. He sent it back. I saw the rifle for sale at the Vintage Cup 2 months later.
Second hand story, a gent bought a vintage Purdey 20ga from a well-known dealer, sometime later he called Purdey for the history, they informed him that he was holding a fine Purdey 16ga.... speculation was that the gun was bought at auction with out-of-proof bbls and re-barreled with the faked 20ga tubes.
I imagine with the records available from many makers, that it's not as easy to pull off as it once was.
