It is being advertised as a No. 7 --
https://www.gunsinternational.com/gu...n_id=101902968
but the engraving on the frame looks like the 1915 and earlier No. 6 to my eyes.
No. 6 1915 Catalog.jpg
The checkering pattern isn't quite like either Flues No. 6 or No. 7. The beavertail forearm has the shape of the early NID beavertails --
1926 NID Flyer 02.jpg
We can tell it is a very early Flues by the juncture of the top-tang with the frame --
No. 6 08.jpeg
By serial numbers in the 186xxx range the Flues frames were changed to have rebates --
186532 01 16-gauge, 26-inch.jpg
where the top-tang joins.
Interesting gun. Wish the dealer gave us the serial number or better yet pictured the barrel flats and watertable.