I think
Smoky Plainsman's question is a good one. It is important to note that mountain men did not disappear after the last rendezvous. Many of them continued to live on the plains and a surprising number continued trapping. Theodore Roosevelt described meeting several old mountain men into the 1880s. There are plenty of references to pistols and revolvers in the hands of early plainsmen in the literature of the period. Way to many to cite chapter and verse for every one, but a few are worth mentioning.
For starters, Charles Hanson wrote an article about fur trade handguns for the American Society of Arms Collectors:
Fur Traders' Pistols Apparently, Mr. Hanson believed handguns were very common among the trappers and traders during the height of the fur trade.
This page from Harper's Weekly form November 1879 shows an older gentleman named Antonio Lopez, who doggedly clung to his "old-fashioned St. Louis rifle" well into the 1870s, and the article mentions "pistols in his holster."
The image is very clear, and appears (to me) to show a holstered revolver mounted on Antonio's belt. It is not surprising that he continued using his old rifle, though. Captain Marcy had this to say about the mountain men and their rifles in 1859:
Tenngun's post (above) mentions Kit Carson having a Paterson revolver as early as 1839, and we know Kit used a pistol in his famous mounted duel with "Shunar" (actually Chouinard), the French-Canadian bully at the rendezvous in 1835. Just for fun, here is a recent image of that duel, by artist Bob Boze Bell:
Jedediah Smith was carrying a brace of single-shot pistols when he was killed by Comanches in 1835. We have a photo of one of them, which was unfortunately stolen from the museum where it was on display a few years ago:
Supposedly, Jed's pistols were recognized when the Indians who captured them tried to trade them in. The Comanches were unfamiliar with the percussion system, being accustomed to flintlocks, and had no use for guns they could not shoot. The image shown above was from the Summer 2011 issue of
Castor Canadensis, the
Newsletter of the Jedediah Smith Society.
George Brewerton reported "six-shooters" in use in Santa Fe in his book,
Incidents of Travel in New Mexico, which was published described a journey he took in 1848. Josiah Gregg, a well-known trader and author of
The Commerce of the Prairies, reported having "...one of Colt's repeating pistols" at some point during his years in the trade, between 1831 and 1839, and at one point in his book (page 105), he described having a pair of them. He reported that a "horseman's pistol" was the preferred arm for buffalo running by Americans, but he was probably referring to single shot muzzleoaders in that statement, although there is ample documentation of revolvers being used for buffalo running after they became available.
Captain Randolph B. Marcy authored
The Prairie Traveler: A Hand-Book for Overland Expeditions, which was published in 1859. By that time, both Army and Navy revolvers were well known on the plains. Marcy devoted space to discussions of firearms at several points in his book. Here he comments on the relative merits of the Army (Dragoon?) and Navy revolvers (page 165):
So, there is plenty of documentation to show that handguns of various descriptions were known and used "in the mountains" even during the pre-1840 timeframe. I doubt
every trapper had one, but Charles Hanson seemed to think handguns were more common among the fur trappers and traders than is generally realized. Colt's revolvers were very well received by civilian and military plainsmen, evidently as soon as they were available. I think a .44 caliber Dragoon revolver would make a great companion for a later-styled Samuel Hawken rifle of the 1850's. For something representative of the period a decade earlier, that M1842 Aston horse-pistol that sold recently would have been perfect... I'm still kicking myself for not buying it when I had the chance!
Best regards,
Notchy Bob