legal notice: This is all SRD so I can type it out here without being sued or jailed.
Single-Action RevolversWhen using a single-action revolver (as opposed to a double-action revolver), the hammer must be manually cocked; the cowpoke using such a hogleg first cocks the hammer and then pulls the trigger to fire a shot. This makes for a bit slower draw-and-fire action, but it allows the shooter to use various feats to fire off more than one bullet per attack (see the Slip Hammer and Hammer down feats)...
Double-Action RevolversDouble-action revolvers are both cocked and fired by simply pulling the trigger, giving them a slight edge when performing a fast draw.Characters using double-action revolvers receive a +1 equipment bonus to initiative checks occurring during a Showdown. In addition, due to their quick operation, experienced gunfighters can use the Double Tap feat to fire off more that one bullet in an attack. However, as a compensating drawback, due to the stiff trigger action, most double-action revolvers of the period were less accurate than their single-action kin. Unless otherwise noted, characters using double-action revolvers suffer a -1 penalty to hit.
Speedloaders hadn't been invented yet, but some gunslingers carried a few extra cylinders with them and just replaced the whole cylinder, which was much faster than reloading each cartridge. I'll rule that a spare cylinder costs 1/10th of the full price of the revolver, so a spare cylinder for a Schofield would cost $2.80 and weigh half a pound.
