I thought at first (and was hoping for you) that it was a bayonet for a Winchester 73 Musket, (also sometimes called the Winchester Export Musket, and the Turkish Winchester) which would make it fairly rare and worth in the range of 700 -1000$ but it's missing a small notch in the barrel ring that the Winchester would have had. Then I thought maybe the 1870 Navy Springfield, but the grip is the wrong shape. Right now I don't know what it is for sure. I guess I'll look some more in a bit and try to nail it down for you. Are you absolutely sure there are no makings on the blade?