The following information comes from the book "The Ithaca Gun Company - From the Beginning" Second Edition by Walter Claude Snyder. Got my copy with a beautiful inscription from the hands of the author 29 April 2006 at the Southern Classic in Sanford NC.
The Lewis model (1901-1906)came right before the Minier model. Page 292 shows a Lewis Model 1S, serial number 56631 with fluid steel barrels. The grade 1 was their lowest/entry level gun. In the Minier chapter on Pages 306, 308 and 309 we find fluid steel barrels on several pictured higher grade guns. Possibly the fluid steel barrels were available on the "stock" grade 1 version of the Minier model, but that is not stated.
2-1/2" chambering, presumably for 12 GA - I did not find any info about chamber lengths.
Hope this helps.
