There was a huge variety of guns in the "Old West". Actually, other than the Army, not many people could afford Colt SAA's, though as noted, that is all that is seen in the movies. While S&W cut themselves out of a lot of that market by accepting Russian contracts, there were still a lot of their guns, along with F&W, M&H, and dozens of other companies as well as the famous gun maker, Anonymous, Inc. In the earlier years, there were still a lot of CW percussion revolvers and they were around well into the 20th century since they were cheap to shoot and didn't depend on what the nearest store had in the way of ammunition.
Just for comparison, a cowboy made $.50 a day, plus food and a bunk when not sleeping out. So not many bought Colt's, which would cost a month's pay, when "Suicide Specials" could be had for $1.50-2.50. I know it doesn't jibe with the movie image, but few real cowboys carried guns. For one thing, a lot of ranches prohibited their workers from having handguns. If a cowboy had a handgun when he signed on, he had to leave it in the office safe; it would be returned when he moved on. Nor did they own rifles. Rifles were issued by the ranch when needed for varmint control, hunting or, rarely, defense.
Contrary to the romantic image, the cowboy tended to be a drifter, working at a low paying "dirty job" just long enough to get some money so he could live until the next job, whatever and wherever that might be.