I don't think it's been refinished. I believe someone has worked over the muzzle a little with a file, but apart from that, everything I see in the photos looks like factory polish under alot of use and wear. All the polish lines I see go in the correct directions,,not necessarily the easiest to do by hand when someone 'restores' a revolver finish.
The lack of the factory mark could be nothing more than a missed stamping as you can expect most anything in war time production.
I don't see any barrel caliber marking either. I think it should have 'Colt DA 45' on the left side of a 1917. I haven't had a '17 Colt around in a while so I'm going on diminishing memory
and the pics of the other '17s posted. Commercial guns may have been marked differently.
Maybe a 'lunchbox' gun? Missing markings (Pony ,Bbl marks, US Inspectors Mark) plus the polish on the barrel looks like it's one step behind the rest of the parts as far as grit.
The underlying polishing marks show the distinct look of the factory. The slight polishing hard wheel chatter especially on the rounded surfaces that becomes apparent when the blueing begins to wear is easily seen on the cylinder and barrel. Orig. 1917 parts were wirebrushed after their final polish (whatever the grit), most probably with oil, to blend the finish just a bit and remove sharp burrs/edges. That's not an uncommon method of putting a decent finish on metal w/o alot of labor.
The 1917 polish was generally not to commercial quality, aside from the earliest ones. It got progressivly rougher as production went on. Rougher polish is one way of stating that they didn't take the polishing to a higher degree. Trying to save production time during war time. They did the same thing in 1911 production.
Blueing was the same process as the commercial production guns but the rougher metal finish makes the blueing appear darker, almost black in color sometimes on the real late ones.
Parkerizing was done to guns by US Arsenal rebuilding programs after WW1.
With a nice bore and action,,I'd probably buy the 1917 shown if I was in the market for one. It's tough to find a Colt N/S for that price from what I've seen around.