Yes, it is a commercial version of the US Army Model of 1917. The identifying characteristics are the small S&W logo on the left side of the frame and the checked stocks. The military version had smooth stocks and no logo.
Assembly in the 1920s is indicated by the lack of medallions on the stocks, but it might take a letter to know exactly when it was shipped. Regardless of the shipping date, I believe the round-top frame and round-bottom sighting notch indicate the frame was manufactured before 1926.
Good looking gun. I would bet that is at least a $1500 item, and maybe closer to $2000. Commercial guns are a lot less numerous than the military units, but I suspect specimens of both varieties in top condition are about equally scarce. There are 1917 specialists here; maybe one of them can give you a better value range.
I have a 1917 with a serial number also in the 173xxx range, but it's not a commercial. Mine shipped as part of the second Brazilian contract in 1946. It was probably assembled from left-over '20s-era parts just after WW2.
