I'd always thought JB Hickock carried Colt Navy's. He is using Navy's in the film up until the final showdown with Kileen. Then he's packing ivory handled Peacemakers. Anyone more Hickock-savy than me know if this is accurate?
Many UFO/ghost skeptics are actually afraid it's all true and don't want it to be.
Hickock used a pair of 1851 Colt Navy revolvers, silver plated and ivory handled, in their original .36 caliber. These were cap & ball, not conversions, and he allegedly drew out whatever shot and powder was unused, and reloaded these every day.
shareHickok/Otis uses double action revolvers on the train nightmare scene and outside the stage coach in the scene with Slim Pickens. Probably swing out cylinder revolvers with ejector rods attached to the side of the pistol to give it a Peace Maker type look. This has been done on many westerns. Some that come to mind are "5 Card Stud" and "Support Your Local Sheriff".
Colt Peace Makers or clones are used in the shoot out in the snow with Kileen and his men.
Hickok's favorite guns were a pair of cap-and-ball Colt 1851 .36 Navy Model pistols, which he wore until his death. These were silver-plated with ivory handles, and were engraved: "J.B. Hickock-1869". He wore his revolvers backwards in a belt or sash (when donning city clothes or buckskins, respectively), and seldom used holsters per se; he drew the pistols using a "reverse", "twist" or Cavalry draw, as would a cavalryman.