Found an old copy of 'Guns of the Old West'. Seems it was Cole Younger's .32 cal. back up gun. The article shows a new box of Navy Arms Co. 32 short rimfire cartridges with it.
To Quote from William Bell in his 2004 article in the same mag mentioned above: "Moore's revolver, which held seven cartridges and looked similar to an 1849 Colt Pocket Model revolver, was produced between 1861 & 1863 and for that time period, had some pretty unique features. It had a single action mechanism like most American revolvers of that period, which required the hammer to be manually cocked for each shot, but was not the usual cap and ball handgun made by Colt, Remington and others. Instead, it chambered the same .32 RF Short self contained cartridge as the Smith & Wesson No.2 Army. Considered adequate for its time, the .32 S&W short had an 80-grain outside lubricated lead bullet that was backed by nine grains of black powder, giving it a velocity of about 700 feet per second (FPS) and a muzzle energy of around 90 foot-pounds. This compares performance-wise to the more modern .25 and .32 caliber automatic pistol cartridges."
Hope this provides you with some useful load data if you decide to fire that beauty. The pics show theirs with a detachable steel rod for ejecting spent cartridges as well.