How do you identify an Ithaca NID from its predecessors? I picked up an Ithaca SXS recently in well-used but not abused condition. It still locks up tightly although the lever rests to the left of the centerline. The serial number starts #380... and I believe it is a pre-NID model. The serial number is stamped on the top of right receiver rail, on the left rail is stamped "S" and the numerals "16" as it is a 16 gauge gun. I had a 'smith check the chambers and they are 2 3/4" but I feel that it probably was a 2 9/16th" originally. The barrels are fluid steel, not Damascus. The only really bad part, and it is mega-bad, is the tock finish. It looks as if simeone glopped on furniture varnish and then left the gun near a heat source. The stock finish is sagging and has alligatored badly so I am planning to refinish it. I loaded down some 16 gauge rounds to about 1000-1050 FPS and ran them through the gun and it handles beautifully.
I was wondering what the model is because there is no model ID on the gun at all, just "Ithaca Gun Company, Ithaca, N.Y." on both sides of the receiver and the engraving of a setter standing in some weeds on both sides.
Ithaca nid's were produced starting in 1925, that is when the rotary bolt and stronger frame were adopted. You can also tell by the serial no. anything 425,000 and above. Your gun would be a field grade flues model. Ithaca made several different models including field, grades 1 2 3 4e 5e 7e and $1000.00 grade or $2000.00 grade after the war.