Hal
You have a Grade OO SAC gun with "Triplet Steel" barrels. I can't give you the composition of the materials that compose the steel in these tubes; but Triplet Steel was the Syracuse Arms moniker used to denote the "fluid" steel tubes fitted to this grade. I suspect these steel tubes would have been similar to those used on lower grade LeFever, Smith, Ithaca, etc guns from this same era; but the collector will find Triplet Steel barrels only on the Syracuse Grade OO gun and the Syracuse hammergun, although I have seen one early Grade A gun factory fitted with a set of Grade 00 barrels. As to manufacture, your serial number indicates a very late gun; so it should have a sliding cocking plate that engages the cocking rods when the fore iron is attached. Guns with this feature were produced from about mid-1903 thru the end of production, which I believe took place in early 1905.
