I aint throwing a wrench in here, but has anyone personally handled and examined this piece? Pics are tough to work off. Best.
Take a common model like a Model 1899 and put a barrel lug or a square butt on it. Does anyone need anything more than a few images to tell it was not correct and could not have left the factory in that configuration? You cannot add a feature like the 3 pin Model 2 frame to a gun that was manufactured before the improvement was even invented. Intentionally gouge out the serial number on the right stock, stamp serial numbers on parts that do not have serial numbers, or stamp serial numbers and assembly numbers on the same part, why would you do that at the factory?
As Powderman noted, bottom line is that I guess all the experts did no good convincing the seller that they owned a fraudulent gun, since it is for sale at a ridiculous price and misleading description.