Mexico 8 Reales - Real coin? [gelöst]

I bought a Mexico 8R coin (KM 377.11) from eBay recently. However, when I received the coin, I found its size smaller than average (in Fig. 3). I talked to the eBay merchant, and the response says the size range of 8R is usually 37.2-40.8 mm, and Oaxaca coins are commonly smaller. I used a Morgan Dollar to tap the edge of the 8R and the sound has a higher tone compared with tapping the edge of Morgan Dollar. Does this overall information indicate that my 8R is likely to be fake?

I have some different 8R coins of that vintage, they are all different diameters.

Does the edge have the security pattern? 

The real question is the weight, if it's under 26.5 grams you may have a concern.

Thanks for your response! Yes, the edge looks right.

I have weighed my 8R coin and it is 27.12g. Is it normal for a smaller coin to have a standard weight?

That is good news. Yes it's normal. It is also a tiny bit thicker than ones larger in diameter.

I'm sure it's fine.

Thank you for your help!