I'm sure you found this, which has an estimated DOM by SN. The “Knickerbocker Hammerless” was listed from 1904 to about 1910, then the “Knickerbocker Improved” with coil spring locks until 1916.
https://www.shotgunworld.com/threads/folsom-crescent-american-gun-co-tradename-information.308330/
and
https://docs.google.com/document/d/1OxZo5Tkvx2G8eYf747QR9B5RJdN6Siu5JGIhfguSXXQ/edit

The 'Armor Steel' rough forged tubes were sourced from Belgium like all the other U.S. doublegun makers. Early on they were decarbonized steel, but by the 20s were AISI 1040
A Crescent tradename gun with the tube maker L. Lochet Habran and steel source Acier Cockerill Liege

[Linked Image from photos.smugmug.com]

The barrels (and gun) were entirely fabricated in Norwich
It is typical to have no other marks on the barrels, but most Crescents I've measured had 2 3/4" chambers.

I am aware of a Crescent bored at about .700". The barrel borers at Crescent were motivated by volume and not quality. Or it could have been the day after St. Patrick's Day wink

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