blackpowder revolver
If it's a Colt style (open top) tap out the barrel wedge far enough that it's only held in by the retaining screw. Pull the barrel and rammer assembly forward off the base pin. Bring the hammer to half cock and slide the cylinder off the base pin. If it's a Remington style (with a top strap) bring the hammer to half cock, lower the rammer and pull the base pin forward and out. Remove the cylinder.