Winchester M97 Trench Gun...opinions?

A few days ago a friend and I went to see some firearms and edged weapons from a local estate. Among the mix was this Winchester 97 Trench Gun. The deceased gent had purchased it from the Suffolk County, NY Sheriff's Dept. sometime in the late 60's and it had been in his possession ever since. From what I've observed there are no cartouches on the stock and there is no evidence that they have been sanded off. According to the chart in the Blue Book the serial # corresponds to the 1941 production of military shotguns. The weapon was reworked at Rock Island Arsenal at sometime during it service life. I know next to nothing about shotguns mil. or commercial so I'd appreciate opinions on the originality of this gun.

Thanks & best regards,
Len
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I am going to tell you what I think you have there:
I think it is an original WWII riot gun that was reworked at Rock Island. I have run into a handful of early riot guns with similar marks. The bomb on the barrel is the correct early bomb seen on guns made before 1941 or so. FK is a known inspector at RIA. The stock was probably replaced (since we KNOW the gun is a rework) and I think it was sanded because the swivel seems to fit way high. In any case, a riot gun would have had a stock without the swivel inlets.
The mag tube is incorrect. It is the riot type with the takedown lever. The bayonet adapter is four row and would not be correct on a trench gun with that low a serial number - and there are no trench guns with that low a serial number! 930,000+ is the start. As well, it is W marked, and those are ONLY found on very late M12's and as spare parts. The W marking was adopted later in the War when it was discovered that Stevens Adapters did not interchange with Winchesters. Ithaca shotguns were long out of production by that time.
The stud on the mag tube does not mate properly with the adapter. It should go in flush. Is there a filled sight hole in the front of the barrel? Is there a choke marking? The bomb on the barrel is a style that could exist on very few, if any, original trench barrels. Take off the adapter and examine the barrel to see if it is sleeved. That was a common practice, as the trench barrels had a larger OD than the standard barrels. I don't spot the pinch marks for the barrel band in your photos, but judging by the end of the mag tube they should be there, which makes it NOT a trench barrel.
Overall, I doubt there would be much collector interest, but you never know. The adapter is certainly worth something.

---------- Post added at 05:12 PM ---------- Previous post was at 05:09 PM ----------

Actually I am in Nassau County. I could take a look at it for you. But I don't think I would change my conclusions. Early riot gun, reworked at RIA, bayonet adapter probably added on much later.

It doesn't have a high collector value as far a market value, but I think it definitely has collector interest. Anyway, I like it, Len.

The originality and condition of collector guns dictate the market price, but some folks have a lot of interest in many guns that carried on in service for years. Nice find, and thanks for the photos!

The FK is the mark of Frank Krack who was the Chief of Small Arms Inspection at Rock Island Arsenal from the Fall of 1941 to the Summer of 1946. So your shotgun was rearsenaled in that time frame.

I tend to agree that it was a riot gun that has been converted to a trench gun. But I'm not certain RIA did the conversion. I don't recall seeing an arsenal riot to trench gun conversion where they left the magazine end cap stop and locking pin on the gun. These were usually removed. And I believe the bayonet adaptor does not fit properly because it is too far forward on the barrel. They sit farther back on the WWII trench guns. Maybe it can be pulled back flush with the magazine cap unless the transverse grooves for the bayonet adaptor were not cut properly.