Diameters Of Cap & Rays 8 Reales Coins From Mexico - All Years 1823 To 1897

OK, just a question for those more knowledgable than me on this fascinating series.
I've got back into coins after one of my many hiatuses (if that's even a word) over the last 50 plus years. I've been especially interested in 1823 to 1897 Cap and Rays 8 Reales from Mexico. I've bought several lately and already had some from many years ago. I have posted questions on weight here in last couple of weeks and am satisfied with finding out certain things I never knew or even thought of concerning different weight issues with cap & rays coins.

But now I am wondering on what was / is acceptable for diameters of these pieces? Most of mine seem to fall in the roughly 38.X mm or so, but I've come across many lately that are noticeably smaller in diameter. I still do not have a caliper, but next time I go to the tool place, I'm buying one. (I'm out in the sticks and it's like going to the big city when I go to the tool store).

So any thoughts on the diameter of these? Even though some are smaller in diameter, they still weigh the same, so maybe a thicker planchet that weighed the same would be acceptable? Are any mints well known for being like that with their planchets? the latest one like this was an 1850 8 Reales from Potosi. Weight is right,but diameter somewhere well less than 38.something. I know these coins are sometimes not perfectly round and vary some, but it's smaller all the way around when compared to other ones. I can only guess until I get the calipers, but I'd say somewhere over one millimeter less if not more.

Sorry I'm not more familiar with how to get certain members that have vastly more knowledge than me of this series, but names like realeswatcher , swamperbob . and Lucky Cuss have answered some of my concerns and also by reading their previous entries, it has been very enlightening.

Thank you all. and anyone that has any ideas or opinions on this, I'd really like to know your thoughts. I'd post a picture of the particular coin in question, but it's only one of at least a half dozen I've noticed this about.