Betwixt time and $$$, I've not yet scrounged up my choice of long guns for the 1840-1865 era. I do have a rather nice sxs 11 gauge double roughly of the period, which has taken the place of my old Bess. Same bore, same loads, two shots instead of one. As a result I'm sort of primed to notice mention of doubles in the literature of the era. I thought I'd note some of these here, both to share and so I can find them again when I want them.
Commerce of the Prairies by Gregg: (published in 1844), "In the article of fire-arms there is also an equally interesting medley. The frontier hunter sticks to his rifle, as nothing could induce him to carry what he terms in derision 'the scatter-gun.' The sportsman from the interior flourishes his double-barreled fowling piece with equal confidence in its superiority. The latter is certainly the most convenient description of gun that can be carried on this journey; as a charge of buck-shot in night attacks to which are the most common, will of course be more likely to do execution than a single rifle-ball fired at random."
The Prairie Traveler by Randolph Barnes Marcy, Captain, U.S.A. (published in 1859), in the context of buffalo hunting:
"If the hunter be right-handed, and uses a pistol, he should approach upon the left side, and when nearly opposite and close upon the buffalo, deliver his shot, taking aim a little below the centre of the body, and about eight inches back of the shoulder. This will strike the vitals, and generally render another shot unnecessary. When a rifle or shot-gun is used the hunter rides up on the right side, keeping his horse well in hand, so as to be able to turn off if the beast charges upon him; this, however, never happens except with a buffalo that is wounded, when it is advisable to keep out of his reach."
The Indian War of 1864 by Eugene Ware: (published in 1911), "On September 28, 1863, we started early in the morning, and camped on Shell Creek. It was quite a long, deepcut stream, but apparently not flowing much water. We camped on the stream a half-mile above where the road crossed it. Captain O'Brien and I went out hunting for ducks, the Captain having bought a double-barrel shotgun and ammunition at Fremont."
Of the following day, he wrote, "Upon September 29, 1863, we marched to Loup Fork, and camped a half-mile from Columbus. Captain O'Brien was dissatisfied with the shotgun he had bought at Fremont. In fact it was a weak gun, and at Columbus he looked around until he found a man who had a large, powerful duck gun, and the Captain traded off his old gun for almost nothing, and bought the new one. As the game would be consumed by our mess, we agreed that the cost of all of the Ammunition should be charged up to our officers' mess. It was a gun of the old type, with a wooden ramrod, but it shot well."
Any other quotes/references? I recall that Logan Fontanelle had a double when he was killed, but don't recall if it was a shotgun or combination gun. There is mention of doubles in Baird's books and Hanson's The Plains Rifle and The Hawken Rifle: Its Place in History.