Interesting topic : I for one remember seeing a Nitro DBL Rifle in one of the African books ,which had a Barrel clamp swivel do dad and a leather Butt-stock over the end and up part way on left side . There was two point strap ,from the Toe to the barrel . The reason I remember it was it's cartridges were on the side of the butt stock ,similar to today's ammo Bandolier .
Found this interesting read : https://truewestmagazine.com/article/rifle-packin-in-the-old-west-4/
A horsebacker also relied on the above methods, especially cradling the gun in his arms. Being mounted gave him an advantage already, so his long rifle often rested between him and the pommel (front fork) of the saddle. A rider who carried a firearm with considerable wear in the fore-end section of the stock had likely logged in many hours in the saddle.
Evidence of two modes of gun carry by a single individual is provided by an excerpt from the chronicles of 19th-century Westerner William E. Webb. During his 1868 venture across the plains, Webb carried his recently acquired .44 rimfire “New Model Henry” carbine, better known today as the 1866 Model Winchester, by utilizing its shoulder strap and also dropping it across the saddle. He wrote, “I became very fond of a carbine combining the Henry and Kings patents. It weighed but seven and one-half pounds and could be fired rapidly 12 times without replenishing the magazine. Hung by a strap to the shoulder, this weapon can be dropped across the saddle in front and held there very firmly by a slight pressure of the body … and with little practice, the magazine of the gun may be refilled without checking the horse. So light is this Henry and King weapon that I have often held it out with one hand like a pistol and fired.”
Some fur trappers and early explorers carried their longarms encased in a soft cloth or skin-type covering. These scabbards were often made of deer, elk, moose or some other Western animal’s hide. The skin was tanned soft so that it was flimsy and cloth-like, with the hair usually removed. Then beadwork, colored cloth strips or panels and fringe would be added for decorative purposes. Trade blankets were sometimes sewn into colorful rifle cases, as was almost anything else that would serve the purpose of protecting the gun from the harsh elements of the frontier.
Slings, which are so common today, surprisingly saw little use in the Old West. Some frontiersmen made homemade versions out of buckskin, strap leather or heavy cloth, which were simply tied around the stock and barrel to form a crude sling. For horseback use, rifles with slings were generally carried in a diagonal position, with the sling passing over one shoulder and under the opposite arm. This allowed the horseman to ride comfortably with the slung rifle or shotgun held securely, but clear of the saddle.
Few American rifles were made with sling swivels in those days, and most of those were produced for the military. The New Haven Arms Co.’s Henry rifle of the 1860s is one notable exception. Some Henry repeaters were manufactured with sling swivels and were reportedly offered as the firm’s military model. A few surviving Henrys with what appears to be proper period-type slings have been noted, but such leather attachments are quite rare.
The Spencer seven-shot repeating carbine was produced with a sling swivel in the stock, but oddly, no provision for a sling was added to the fore-end section. This is because the company saved money by using one stock for both its rifles and carbines. The carbines were also fitted with the traditional cavalry-type carbine sling slide and ring, found alongside the gun’s left side of the receiver. Some users rigged up homemade straps for use with these carbines, depending on what models were being turned out by the factory at the time.
Commercially-made saddle scabbards, which are so commonly associated with the Western horseman both then and now, made their first appearance around the same time as the metallic-cartridge firearms. These longarms were generally shorter, lighter and much easier to handle, and their sleek lines made them more suitable to use in the saddle.
While some saddle-attached scabbards existed in the pre-Civil War years of the muzzleloader, such scabbards were usually the product of individual efforts. The lore, firearms and equipment of the American frontier reveals little evidence, in the way of existing specimens or photographic or illustrative proof, of their issue before the era of metallic cartridge arms. The few specimens noted were employed by the military during the Civil War, and again, those were homemade saddle scabbards, not commercially-produced models.