I have a Ithaca Model 37 Trench gun , 20" full choke, parkerized finish, plain oil finish stock, overall excellent condition. Also came with a Waffenfabrik Neuhausen bayo & metal scabbard. According to the s/n it was produced in 1969. Looking for any info & values.

1969 is kind of late for a Trench Gun. Any martial markings? Pictures help

eta- https://www.americanrifleman.org/articles/2020/5/27/the-ithaca-model-37-a-forgotten-trench-gun/
written by Bruce Canfield. And the late 1960's Vietnam Model 37s did have Trench Gun bayonets.

This.  Actual Police or Military guns have CYL (Cylinder) or IC (Improved Cylinder) bored barrels.   Full Choke is usually 99.9% a cut down.

I did see full choke 870 Police Barrel that had been special ordered by the US Department of Justice for Federal Prisons.   It was an Odd Duck, but it WAS factory marked and infact Full Choke on a 20" parkerized 870 barrel.  Came in a trade to a Police supply wholesaler from some Federal Prison exchanged shotguns.

A authentic US Trench Gun (winchester 1897, model 12, Stevens 520 or 620 or Ithaca 37) will be fitted with a heatshield Mount with Bayonet lug for the US Model 1917 (Enfield) Bayonet.

WWI made bayonets were used in WWI & through WWII.   With many of the old M-1917 Enfields given away as Miltary Aid to various countries during and after WWII supplies ran low when Vietnam cranked up in the early 60's.

The US even ordered new made 1917 Bayonets for use in Vietnam by a couple of military contractors in the late 60's.

The Correct bayonet that should be on any US Trench Gun (excepting the 870s & 590s) is the M-1917 bayonet.

A dime will not fit into the muzzle end of a 12 ga. full choke barrel.  Dad used that to check old shotguns for years.  A dime.  Easy.  If the dime will insert into the barrel it sure as hell ain't a full choke 12 ga.

In the mid 70's, all the Win. M1200 riot guns in our armory had M1917 bayonets for them.  Wicked looking compared to the bayonets we had for the M14's.

Thanks for all the info. Bore measures @ .695 (dime will not come close to going in.) There are no special markings. Gun was in a law enforcement armory until 1978. I bought it before it ever saw the gun rack.  Ithaca informed me of production date but said all other records were "lost" when company changed hands yrs ago. I have pics, but clueless on how to put them here? I have read every article online, but this info is mostly about government weapons. And they had been in the armory since they had been bought. Thanks again for all info

1969 should have a SN range of 1042001 - 371091500

So, Ithaca built 37s they marketed to prisons and jails that had a 20-inch barrel with a full choke (they also did em with skeet (SKT) chokes). Did not know they made Trench Guns with full chokes, but it wouldn't be surprising. The last tell in your investigation might be to see if the barrel has a hole in it for the front sight (or the remnants if a front sight bead are still present).  A real ;) M37 Trench Gun would never have had a front sight installed in the barrel as it was to have the bayonet mount. A conversion would either have the front sight removed leaving a small hole in the top of the muzzle end of the barrel, or have the front sight cut off leaving the brass stud. Either way it would be visible just looking down the bore from the business end.

Mil gun should have ord markings and proofs, otherwise going off the odd choke size it would be a law enforcement special order.  Heat shields were available commercially too.

My M37 is missing the heat shield.

It was a Vietnam MP shotgun, or so I was told.
It has the provision for the heat shield. It has the bayonet mount.

It's not styled after the winchester trench gun, it's basically a featherweight deer slayer that's been factory modified to accept a bayonet and heat shield.

The police special has the extended magazine tube that goes the full length of the barrel.
Neither have chokes. Both are slug guns.

When they were provided with a factory bayonet shroud,  Ithaca trench guns had the heat shield welded to the bayonet lug. It’s a one piece shroud. Only trench shotguns I know of with two piece heat shield bayonet lugs that are separate components are the Remington’s specifically the M1910, the M870 and the 7180/7188’s.  Modern military Mossbergs can have a heat shield but the bayonet lug is part of the barrel ring assembly.

Here’s an article on military 37’s. The rarest are the WWII guns as there were relatively few made.

https://www.americanrifleman.org/articles/2020/5/27/the-ithaca-model-37-a-forgotten-trench-gun