From 1915 through 1919, the low end Ithaca Gun Co. Flues Models, Field Grade, No. 1, No. 1 Special, and No. 1 1/2 were in a constant state of change. It began in the summer of 1915 when the bold floral engraving was introduced on the No. 1 1/2 --

Then the zig-zag border engraving which had been the No. 1 1/2, became the No. 1 --

By December 1919, the No. 1 Special had disappeared and the No. 1 and No. 1 1/2 were combined as the new No. 1 --

Ithaca all through that time period was phasing out their composite iron and steel barrels (Twist and Damascus) and certainly using up Krupp tubes, which had fallen into disfavor during the unpleasantness in Europe, on product which was never catalogued with Krupp barrels.
Along that same line, I've seen A.H. Fox guns of about 1920 vintage with barrels roll-stamped
CHROMOX FLUID COMPRESSED STEEL on top, but showing vestiges of Krupp markings on the underside. We've also seen a Flues Model Ithaca from this period that appeared to have steel barrels but when refinished one tube showed up to be Twist!!