CWT -F-141/307---Copper (R-1) or Brass (R-8)? opinions appreciated.

TPRC

I purchased a fairly large number of Civil War Tokens from my favorite coin dealer, who bought a large collection, including the one shown below, an F-141/307. The CWT collection I purchased if from was meticulously researched and unusually accurate.

This particular token was listed as brass, which is r-8. The copper equivalent is r-1.

I sent the token in ATS and, as expected, it came back as brass, f-141/307 b; however, I did not like the designation/grade. So, I cracked it out and resubmitted it. This time, it came back as unc, but it also came back as copper, f-141/307 a, not brass, a "b", which is disappointing. but OK, if it is accurate.

I put the piece into my dealer-friend's analyzer, and it shows as noted below, with 76.4% copper and 9.3% Zinc, as well as some trace elements, including palladium, and tungsten, as well as some gold. I did this in the slab, FWIW.

So, the question is, is it copper or brass, or something else, or is the machine, which was recently calibrated, messed up? I understand that generally for a composition to be brass, it requires 25-30% zinc, but I don't know if that rule of thumb applies to CWTs from the 1860s.

DCW

It sure looks copper from the photos, so I can see why the TPG labeled as such. Brass civil war tokens usually look yellow-gold if they are uncirculated, or a dark brass look that an tone wildly. Yours looks pretty brown.
But the analysis seems to suggest brass (Copper and zinc)
I think NGC provides metal analysis if you pay. They'll even out it on the label (if you pay more 😆)
Nice token

TPRC

In hand, I see it as brassy. Does anyone know how much zinc a brass token from 1863 is supposed to have. I will talk with NGC about it. Even as an R-8, it's not exactually valuable.