I was going to post it, and then got busy, and then forgot about it, but an article in the last issue of Montana magazine, written by a fellow who was a trapper in Montana in the late 19th Century, noted that he was taught by an older more experienced trapper to carry his rifle in this manner. He noted that he found it dangerous when riding through the woods, but then you had it handy if you needed it.G.KUSH.UE wrote: The MP carried their Winchester Model 1876 carbines (calibre .45/75 not .45/70)across the saddle "frontier" fashion. Contrary to Hollywood this method of carrying the rifle was the most popular method of carrying a long arm on the frontier, especially during the early years when hostile Indians were often encountered.
I have to laugh when I see all of these U.S. Cavalry reenactors charging around with carbine slings, boots, sockets, etc. The single most popular method of carrying the Springfield carbine in the field was directly in front of the pommel, crosswise.It beat heck out of the saddles but that's what they did. The regimetal saddlers made slings to fit the McClellan and when slings were not available the troopers would remove the snap hooks from the regulation sling and attach it to their waistbelts, shift them forward and snap on their carbines.
I guess I should note here that you can find quite a few interesting accounts written by trappers in the 1865 to 1920 time frame. It's widely assumed, and even repeated in pretty good histories, that trappers disappeared prior to the Civil War but that's simply untrue. Completely untrue, in fact. In spite of the oft repeated story about the "beaver disappearing", trappers didn't disappear at all, nor did the beaver. Trapping changed, however, in that the widely free ranging lifestyle they had before the Civil War slowly died out. By the early 20th Century they tended to operate in smaller ranges. Having said that, there were still full time trappers in the US at least up until WWI, and in Canada beyond that.