A major factor is whether it has been altered or messed with. The following will slash the value in half or more: sanded or refinished wood, re-blued metal, shortened barrel, shortened mag tube. From what I can see in the photos, I cannot see any evidence for alterations, although the barrel length would need to be carefully measured in inches and compared to the factory information from Cody. There are so many altered Winchesters out there, it isn't funny, so the Cody information can either raise the value of your gun or expose it as messed with. You have a special order Winchester with its half octagon barrel and half mag, which does raise the value, and it is in a desirable caliber. For Pete's sake, do not mess with it. As for value, that is tough to say. It depends hugely on the original condition. From what I can see in the photos, you would have a 'brown gun' where the original blue has been replaced with a dark patina. This puts your rifle at the low end of what an all original '86 would be worth. As for value, there are more knowledgeable people on this forum than I. I traded away a similar 86 a little less than year ago for about $2,500. However, mine was a full octagon half mag made in 1904. Yours is a half octagon half mag, which increases its value and yours was made pre-1898 with a case-hardened frame, which also increases its value. On the other hand, I've seen some '86's sold more recently for quite a bit lower than what I would have expected. When all is said and done, assuming your gun has not been messed with, and assuming it letters with the Cody factory information, and given it has a half octagon barrel in 45-70, and assuming it has a good bore and mechanics (which I don't know if it does) if it were mine, I would not let it go for less than $3,000. It might be worth more depending upon how nice the original finish is on the barrel and mag tube. Like I said before, there are others here who have a better idea of its value. I'm just giving you my own thinking on it.