Any chance you can post a photo? The .44-40 (.44WCF) chambering was an option in the .44 Hand Ejector series, but the question is whether this would be a first model or second model revolver. The transition occurred in the 15000 serial range.
Does the gun have an ejector rod shroud under the barrel, or does the ejector rod hang lock in place under the barrel and remain visible from both sides? If the former, it is a very desirable first model; if the latter, a second model.
Depending on condition, which I take to be pretty good from your description, this could be a fairly valuable gun. If in original condition, it is probably worth well over $1000; if refinished, it would not be worth as much but would still have appeal as a collectible.
The gun probably shipped in 1917. Other guns in that serial number vicinity did so, and some chambered the .44-40 round.