There are a lot of variables among imported C&B revolvers, bore diameters and chamber diameters are perhaps the greatest variable as you can see from some information posted above. For best accuracy with any revolver, C&B or modern magnum, the bullet should arrive at the forcing cone at least as large as the groove diameter of the bore and .001" or .002" larger may be even better. Therefore the diameter of the chamber mouth must not be smaller than the groove diameter of the barrel. Cap & ball revolver often have chamber's very much under bore size and can be greatly improved by reaming. Without knowing the exact diameter of your revolver's barrel I think I'd not be going very far out on the limb to say "if a .451" ball fits the chambers tightly then they need to be reamed".