Heck, I just looked at the mint marks of these things, I think that I was wrong stating mine is an S and yours was too.
( So I edited my previous post ) There is an extensive list of mintmarks so I don't know my stuff there.
It's possible mine is from Mexico City and yours might be from Hermosillo KM#377.9
Take a gander at this link.
https://en.numista.com/catalogue/pieces7394.htmlYour weight looks right for the coin. You may have a scarce mint coin there with a much lower mintage than usual. Best of luck.
Edited by TNG
08/12/2017 3:21 pm