Gambrinus, the chart you posted seems to not tell the diameters of any civil war era pistol bullets. It appears to cover metallic-cartridge bullets from the Indian Wars era through the 20th Century. Non-metallic-cartridge civil war bullets tended to be larger in diameter. According to the "Handbook Of Civil War Bullets & Cartridges," the .44 Watervliet's unfired diameter is .455" to .456" -- and the .44 Potter's diameter is .452-inch. For dug civil war lead bullets (like Alan Payne's), add a few thousandths for the thickness of the lead patina... and you'll get the diameter result he got.
A few other civil war .44 revolver UNFIRED bullet diameters, from the Handbook:
.455" Colt Army "New Model".44
.455" Richmond Arsenal Colt .44
.458" Sage .44
.461" Starr 2nd Model .44
.462" Dean & Adams .44
.465" Kerr .44
.469" Starr 1st Model
Hoping this info is helpful.