Here is a perfect example of somethin that looks good at first, but a close examination shows a completely made up Trench Gun:
The serial number is between the range of WW1 and WW2 Military shotguns. Way too early to have a "U.S." and Flaming Bomb on the left side of the receiver, in fact the first guns marked this way (in the low 900,000 serial range), only had the "U.S." with no Flaming Bomb. A close inspection would no doubt show these marks to be inscribed, rather than stamped into the metal.
The "W.B." marked stock would also be right for an early gun in the 900,000 serial range, on a short comb stock. Not a high comb stock like this one. Nevermind that it looks like it was just put on there yesterday either.
The "CYL" marked on the barrel, next to the lined out "Full" is also very suspect and in much larger letters than the military used.
The handguard appears to be a repro also, as evident by the flat sides at the rear of the heatshield, and rough look at he bayonet lug.
The whole gun has been reblued to hide the suspect military stampings, but it does look very shiny!
The final detail for me is the lengthy disclaimer at the end of the description, stating:
"This is sold as is, so if you doubt the originality of the item, please do not bid. We are not making any claims as to its history/originality, because we just don't know enough about this item."
I suppose it really could be true that they don't know about it's authenticity, but they sure went out of their way to make sure it was clear. At least they are not claiming it is a "Military" shotgun.
I hope no one on this forum winds up with it thinking it is something it is not.