Mike's post is pertinent
I think Mike is right (although I can't cite any evidence, only what I know of human nature and the humanist approach to econimics) about a lot of folks carrying extra cylinders. I said only that only that it was possible to do so.
I also think, (again with not even a shread of evidence) that not every male who lived in what was then the Wild West felt it necessary to carry a firearm. Remember that in some cases, the firearm absorbed resources which might have been directed at what the individual saw as more pressing needs.
We might have a fairly decent idea of how many revolvers were available because we know in general terms how many were manufactured or perhaps imported. While this does not enlighten us as to practical numbers at least it tells us roughly what the maximum number would be. We also have records of the fixed population of the various states or territories from the years between say 1870 and 1890 or so, not counting transients who might not have been included in the official population.
From those numbers we could do an extrapolation. If there were for example 3 million revolvers available of all descriptions, and 21 million inhabitants, then there was 1 revolver for each seventh person. Obviously those numbers are only examples.
I also agree in principle (principle only because I can't cite any evidence) that it was very likely that a person who happened to sell firearms also sold dry goods or other stuff. I bought my first rifle from a hardware store in about 1962 in a small Pennsylvania town. The gun (Thats right, you caught me using the term "gun" applied to what is more correctly small arms ;o) .) rack was right across from the nail bins.
I wonder about such questions as, "How large did a town have to be to support a general store which sold firearms as well?"
"How much larger was the town that could support a merchant who sold only hardware and firearms?"
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson