Out of a large number of C&B pistols I own, only 3 shoot with what I would call good accuracy.
These pistols are older Italian guns.
The best shooting is a Uberty 1861 Colt Army .44,
a Navy Arms (made by ?) Rogers & Spencer .44 and a CVA 1847 Walker .44. Each of these is capable of 1 1/2 inch groups at 25 yards.
I find it interesting to note, two of these guns are the "open top" Colt design.
All three of these guns share a common condition. The size of the chambers are all between .001 to .004 larger than the groove diameter in the barrel.
Of the pistols I own which are not as accurate, the chambers are from .000 to .003 smaller than the groove diameter of their respective barrels.
This undersize chamber sizing (or oversize barrel grooves?) seems to be a common trait among the guns recently manufactured.
I was told that chamber sizes like this are the manufacturs way of assuring a tight fit of the ball. Why the barrel grooves are larger than the chamber size, I cannot say but it sure doesn't help accuracy.
One of the common "fixes" to give C&B guns target accuracy is to hone out the cylinders chambers so that they are about .002 larger than the barrels groove diameter.
IMO this is rather safe in the .36 cal guns because they have a lot of wall thickness between the chambers and between the chambers and the outside of the cylinder.
In the .44s there is very little wall present so the idea of reducing it to accomodate an increase in chamber diameter has its risks.
Another thing to consider if enlarging the chambers is being considered is the barrel groove diameter.
In the case of my .36 cal Remington Navy, the groove size is .373. The chambers measure .372-.373.
If I were to hone the chambers to .374-.375 to provide a good fit with the barrel, they would be the same as the standard .36 caliber ball (.375). This of course would not be oversize enough to assure a tight fit of the ball in the chamber.
In the case of the .44s, there are the .457 diameter balls available (which the Ruger likes), so honing the chambers is practical, although as mentioned, not without its dangers.