One other thing I see from looking at the site is....

the top rifle is an 1853 Enfield Rifle MUSKET. This musket part and the fact they do not list the twist of rifling for the top rifle makes me believe that it is a true musket.

this might have something to do with the lack of accuracy in the rifle....I am not that up on Civil War rifles....

One forum you can come to and get some answers is

Muzzleloading forum

there are people there that shoot only muskets and smoothbores like what you own. I am sure the would have much better suggestions then what I can offer you, and would welcome the chance to help you...