The face struck me as modern, and mold seam, or lack there of, pushed me more in that direction. Do all the USA buttons have the seam?
I'd never trust the look of the metal, just look at it as another factor because you could always get an oddball mix.... and then you add in some good ground conditions and you could have a pretty impressive looking button. As you know just digging a little deeper can make quite a difference in condition, and that was the case for me never seeing a Rev War pewter that wasn't completely oxidized white... until I dug one from about two feet and it was mostly grey. In fresh water you can get some brown color on pewter or lead, which is another reason I wouldn't try to judge something based only on the color or what looked like a certain metal composition.
PS: Most that look that good are too good to be true, but detecting miracles can and do happen!
oh, and I think CC calls it fake because it's nicer than his.