That might be as good as its going to get. Your down to the clean copper in some spots. I hate these finds. You know you found something good but you're forbidden to know what it is.
I had the coin in the tumbler over night and by first look it made it a little worse. Oh lord I hate and love those finds......damned farmers using manure fertilizing fields and pastures which destroys the metal except for silver. But silver coins are very rare - only found 3 in 7 months of detecting. Still learning the Nox 800 but gettin' better at it.