1877 Ho 8 Reales - Failed Alteration Attempt?

I think you're right on the money Numismat .

Reminds me of a 186X Ca JC 8 well worn reales I have. Some idiot drilled a hole right in the last number of the date. And I think it was purely by accident, unlike your coin if you're right. It could have well been an 1866 one the one I have. But The JC assayer initials make it one of several years that decade from Chiuahua.
Bummer.

That was a nice GC one they did that to Numismat !
It's a shame when they do it to rare mint ones. I was going to try and collect a set of at least one of every mint 8 Reales C&R, but the hard three (including GC like yours) are pretty pricey. The whole series of cap and rays seems to have really taken off. I'm glad I obtained most of my set when I did.
I'm mainly still going for a one a year from 1823 to 1897 8 Reales set. Have all but the 1866 (naturally the hardest one to obtain). And at least I should upgrade my 1827 that has a hole in it too and my 1828 that has a very, very weak date.
I wish the person that drilled my 186X JC from Ca had left enough of that last number visible so I could identify it as you can your Guadalupe y Calvo. Even if it wasn't a 1866, would have been nice to have known what year.
Thanks for sharing it, I still like yours even with the hole!