ATW525 is correct; the term "tuning" as applied to a revolver generally means smoothing the action, rather than correcting the point of aim.
The Rogers & Spencer is a solid frame revolver with fixed sights, so getting it to "hit where it looks" is not as easy as if the sights were adjustable. You might try other variations in the loads, but I would not be too optimistic about results. You don't say whether the gun is shooting "off" to one side or in the vertical plane.
If you are willing to put up the money, you can have the barrel slotted for an adjustable front sight, which would solve your problems by allowing movement to left or right; the sight would be made high and then filed down as necessary.
The fact is that the makers of BP revolvers really don't care much about proper sight adjustment, since they are making toys, not serious revolvers. That was not true in the old days, and most antique revolvers (if not messed with) will shoot close to the point of aim.
Jim