The following is from "The Bugle, Quarterly Journal of the Camp Curtin Historical Society"
"Originally, loose gunpowder was poured into the chamber and a bullet added. By the time of the Civil War, paper tubes were attached to bullets to create a single piece cartridges.
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The cartridges would be pushed into the chambers from the front of the
cylinder. A loading lever under the barrel would be pulled down and a plunger would seat the cartridge in the chamber. Then, a small percussion cap would be placed on the nipple.This process would have to be repeated
for each chamber. Thus, unless there was a long lull in a battle, it was unlikely that a revolver would be reloaded.There is no reliable documentation that soldiers carried extra pre-loaded cylinders and
interchanged the cylinders to reload their weapon"
It should be noted that mounted troops issued revolvers also had a small leather "pistol cartridge box" mounted on their waist belts, to carry additional paper cartridges.
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This a long debated issue. There is evidence of two cylinders in some custom cased sets, but this was not common. Issued revolvers to cavalry and artillery enlisted show no evidence. Cavalry weapons were in order of importance, until after the Civil War, was saber, "pistols" and then carbine, Southern cavalry, particularly Texas and Arkansas were know for their multiples of revolvers each man carried. Often two holsters on a waist belt, one or more tucked into the waist belt and two carried in saddle pommel holsters.......this was a carry over from Texas independence days and Colt Patterson revolvers, where most Rangers were issued of the "reissued Texas Navy revolvers" two each, giving them 10 shots in addition to what ever long arm they carried. Confederate volunteer regiments, typically didn't carry sabers, so the revolver was their primary weapon.
My uncle found a '51 Navy revolver laying on the ground of our farm in Quanah Texas, so corroded that only the steel parts were left. In the cylinders were a few conical .36's still wrapped in paper.