Another nice coin!
You appear to have the 1916-S with a minor double die reverse, listed as
1916-S DDR-001, 1-R-IV+VIII on Variety Vista. The die clash with readable "UNUM" beneath the Indian's chin, strong clash through UNUM, and small die breaks from AM of AMERICS to E of EPU and from R of AMERICS to PLURIBUS are markers. While the photos are not clear enough to be sure, the markers appear to be present, and I think I can see the doubling on the west side of the right front leg.
Likely because of the die clash, the dies were polished fairly aggressively. This is why the Buffalo's left rear leg is weak and there are multiple N-S polishing marks from the Buffalo's hind quarter to EPU. Obverse polishing marks are evident from the Indian's nose to LIBERTY, below the third feather, and west of the second feather.
The strike is soft, but not abnormally so for the date and mint. Unlike some early branch mint coins, however, sharply struck 1916-S Buffs do exist, and in sufficient quantity to keep prices reasonable. (There are also some ridiculously weak 1916-S coins, and even a known die transfer counterfeit of a heavily circulated (G/VG) 1916-S.) The full horn and clear split tail offset some of the weaker aeas on the obverse. Overall, I would rate your coin's strike as very slightly softer than average.
There are extensive small contact marks on the obverse and reverse. On the obverse, these are most evident on the rim, cheek, and second feather. On the reverse, the contact marks are evident on the Buffalo's upper left leg, hairline above the front left leg, hindquarter, field below the Buffalo, and one particularly hard edge hit visible to the rim above the second T of STATES.
I don't see evidence of circulation. The areas with weaker details appear to be the result of strike weakness or die polishing, varying by the location of the weakness.
That said, the photos suggest that the coin
could have been cleaned or dipped some time ago. The surfaces do not appear entirely natural, but that could be from lighting, rather than an older cleaning or dipping. The difficulty is that NGC in particular seems to accept dipping. The only place I see what
might be surface scratching from cleaning is to the left of the Indian's eye and on the Indian's eyebrow. That could be bag abrasions. Again, this could also well be from lighting, rather than on the coin.
If the coin hasn't been cleaned (again, what looks like possible cleaning might just be lighting), I see a grade in the MS-61 or MS-62 range, taking into consideration strike weakness.
It would definitely be worth checking the markers for the possible
DDR. If this is 1916-S-DDR-001, you might want to consider taking advantage of the variety certification.
It's a good looking coin. Thanks for sharing it with us!