Normally, because Cap and Ball revolvers are loaded with Lead RBs, you need to use a ball diameter that is Larger than the diameter of the chambers, so that a good SEAL is made when the ball is pushed into the chamber. A ring of lead is commonly scraped from the sides of the ball as its seated in the mouth of each chamber.
Because the balls are NOT loaded with patches around them( as we do with rifles) even using a wool or fiber wad down the chamber behind the ball does Nothing to hold the ball IN THE CHAMBER until you fire the gun! :shocked2: :idunno: :surrender:
PLEASE, measure BOTH the actual chamber dimensions for all 5 or 6 chambers of that cylinder, and then ALSO measure the diameter of the Throat at the back of the barrel. The two diameters need to be close to the same size to get any kind of accuracy from such revolvers.
Sadly, its Not uncommon to find the throat in the chamber( the front part where the ball is seated) to be SMALLER in diameter than the throat of the bore, sending an undersized ball into the barrel, to rattle down, gas blowing by it in the barrel, and going who knows where once it leaves the muzzle. A basketball size group at 30 feet is usually the result.
These guns can be made to shoot accurate, but it takes some work, and money to do so. The Alignment of Each chamber with the barrel has to be first established. Its not uncommon to find one chamber in 6 to be WAY OFF Center. Then, the throats of the chambers can be reamed to the larger diameter of the barrel.
My brother has a .44 cal. revolver that ha chambers that didn't line up with the barrel well at all. They have been redrilled, and you can easily see how off-center the original chambers were made by the "shelf" that now appears in the sides of the cylinder after the new drilling, and reaming. Instead of shooting .445 balls, he now shoots .457" balls in that revolver, as that is what fits the barrel on the gun. Even .454" diameter balls would fall down that original barrel- that is how badly the gun was manufactured originally. ( .440 vs. .457"). :thumbsup: