
I picked up an Ithaca M37 Riot - Vietnam era (Serial number puts it made in 1973)
There is a Defense Acceptance Stamp on barrel. Dual "P" proofs. One on Barrel, one on receiver.
I would rate the condition at 80% to 90%. Price - A little high, at $600 but it does have the Defense Acceptance Stamp on it. Other wise it does fits into my small Trench/Riot Gun collection. (Originally the collection was only WWI era)
Remington M10R (1918)(US Proofed) (Shame it was a reBlue - still see US markings - The US ordnance dept. did reblue these shot guns during the rebuild process in the 1940s, but shame it was done no matter who did it)
Winchester M1897 WWI trenchgun(1918)(US Proofed) Pitted and looks the part.
Stevens 520 WWI riot (US Proofed) (Later was a WWII reissued to Japanese Internment camp - Crystal City Texas (Stamp marking in butt stock confirms this) A true Gem.
Ithaca M37 Riot - Not US marked but parkerized, with eight shot tube (From a Canceled Foreign Military Contract from the 1980s)
I have now picked up 3 riot shotguns in as many months.
As requested here are the pictures:

The Stevens Model 520 Receiver and Barrel markings.

THe Crystal City Camp - CCCamp TX (It was the largest US Department of Justis camp)
2-41 Over hauled in date

Remington Model 10R Markings US on barrel and Receiver.

Model 1897 Front end towards enemy

The shallow pitting prevents me from grease penciling the markings.

The M37 1980 canceled military contract riot gun