Remember that Col. LeMat designed a combat weapon, not a target arm. A good majority of original reference calls them the "Grapeshot Revolver" which, besides it's nine shot capacity, was it's real selling point. It's original design was for .42 caliber cylinder and .63 grapeshot barrel. The U.S. ordnance report of May, 1859 says .41" bore for cylinder chambers and .65" for the shotgun bore. The military tests were done with 16 grains of pistol powder and a 0.75" long "elongated ball" projectile. These appear to have been pre-made paper cartridges, though those may not have been available that early. The "grapeshot" barrel got 40 grains powder, unspecified as to type, with a paper cartridge with 15 buckshot or round ball, actual size about .640" since it weighed 406 grains. Their results on wood penetration at 30 paces was 2.5" for the "elongated ball", 2.5" for the round ball from the "central barrel", and 1.0" for the "Buckshot at 15 paces....". As you can see, the gun was designed for combat at combat ranges.
You must also remember that the loading lever was designed to be held by friction through a hole drilled slightly off-center. The lever also changed sides on the gun during it's production, early ones on the right and later on the left as now done on the replicas. Pietta went with a more standard .451" cylinder diameter and 6.75" long barrel instead of the 7.3" length on the originals to prevent forgery. According to DGW, the bore is 7 lands of .440" & 7 grooves of .452". They also recommend a 22 grain load of FFFg for .451" balls and a 30 grain FFg load with a .630" ball or .75 ounces load of buckshot. These sound reasonable. A friend had one of the first model out some years ago now and we found these loads about max for comfortable shooting considering pistol weight and grip shape.
The three different models now available are called Army, Navy & Cavalry and vary only by spur trigger guard, lever type barrel release & lanyard ring on the Cavalry version; round trigger guards, knurled pin barrel release & holed butt cap on the Army & Navy versions. These two also vary with the Army having the cross pin barrel selector while the navy has a spur type selector that pushes up and down. They're certainly interesting but I prefer the Colt design, especially for comfort in shooting. Your mileage may vary! :wink:
If you'd like to read more in-depth accounts of LeMat's guns, I'd recommend that you check around for copies of "Confederate Handguns" by Albaugh, Benet & Simmons or "Firearms of the Confederacy" by Fuller & Steuart. These date from 1963 & 1944 but your local library should be able to locate copies under their library loan program. The first is a detailed history of the guns while the second is a good source of original correspondence about contract and delivery from Confederate sources.