In his book-Good Guns Again-pages 39-40: "Ithaca is America's Plain Jane boxlock---- Ithacas have boxy silhouettes, coarse engraving, and were the least expensive of the good American guns. They were also rugged, simple, featured a fast lock time-- and were available in all gauges from .410-28 and the Magnum 10.
Potential Ithaca users should confine themselves to the NID, the double made after 1925. Pre-1925 Ithaca doubles (Flues) have thin fences, they also have a sliding cocking piece on the bottom of the barrel lump. NID guns have the rotary bolt ( as on L.C. Smith and A.H. Fox-- my addition to Bodio's words) they are chunkier, more substantial looking guns---""
I like Bodio's writings, and one reason, of many, I like this book is that he loves the M12- as do I. He is not so keen on the M21 though. And like the late Michael McIntosh, he favors the A.H. Fox guns--
Hope this answers your question-- RWTF