If the show made cap and ball guns popular , there would be no sale, demand would be high enough that the marketing guys wouldn't have to reduce the price.
I just barely remember the national sudden popularity of Davy Crocket back in the mid 50's, The theme song was played on the radio, and folks cancelled other activities, gathered round the Tv to watch. Every body watched. Coonskin hats and licensed products were in high demand. (I still have my coonskin hit) There was a series of air rifles that fired 1/2 inch cork balls, and even came with a bonded leather possible bag. (Had it but wore it out)
Seeing another massively popular frontier/western genre movie or show like that is unlikely. Don't get me wrong, I really like Hell on Wheels. I just don't think it is the show to make cap and ball revolvers a big fad.