There are a handful of Buffalo nickels that you can tell the date on no dates by some unique details, although this one has some corrosion that makes it a bit more difficult to be certain. It does look to have the wavy left ribbon style which was used in 1920 and 1921. 1924 is a possibility (has smaller waves) but I think less likely. The 1921 buffalo's have enhanced hair detail going into the braid which I don't see here leaving 1920 S as most likely in my opinion.
I can't tell with the corrosion if it is a two feather but 1920 S does have a 2F variety.
I always used vinegar with a few good sprinkles from a salt shaker. Mix it up good and by morning you'll have your answer. It destroys any value but your coin isn't worth much at all. Experiment, have fun.
It definitely not going to hurt the value. I say hit it again and maybe we can find out if it's a 1920 S. If you can let us know if the small feather between the neck and the largest feather is there. I think I see it some trace of it in the last photo.