The Notorious Massachusetts Oak Tree Shilling

I picked up this coin on ebay. Here's the previous Heritage sale from the Salmon Collection. Their photos are better than what I can do, though they're a poor resemblance to the dark shilling.

https://coins.ha.com/itm/colonials/...bnail-071515

The seller sent the Heritage material. Someone had slipped a handwritten Fake Coin note in with it. There are some strong opinions about it. Yet NGC slabbed it. And there is only one in existence.

To me it looks like a heavily clipped Noe-5. It's 15% light. The parts of the coin with the diagnostic die cracks are missing.

My main question is whether it's the modern fake many critics think it is. Yesterday I went to the LCS for XRF's. I took a 1653 Commonwealth shilling and a Mexico 1630-1660 8R cob along for comparison. All three tested identical at 98-99% silver and 1-2% copper in the holders. I have seen similar high silver measures on other 200+ year old silver coins (surface depletion of copper maybe). While this doesn't necessarily prove authenticity, it's silver and similar to contemporary silver coins. If it's a fake the counterfeiter succeeded in faking the aged composition of a 1652 shilling exactly.