Not to be a debby-downer, but if you used that gun in a consecutive four shot back to back, the barrel would explode.
Also, the model is off.
That's a pepperbox gun.
As for being used in the Civil War, I have absolutely no idea if it was used or not. But it upsets me that you went for a shot-gun action type gun like the Pepperbox and not the LeMat revolver. I am by no means a professional historian of any degree or college, but I can guarantee that all my 10 years of teaching the locals at every reenactment recreational center by North Carolina I know my stuff when I'm talking.
The pepperbox was occasionally used in an early-guerilla tactic but I seriously have no clue when they were enforced majorly on a battle. Plus, as I already said: the barrel would overheat and blow up if you use it back-to-back-to-back-to-back. The LeMat revolver would be a much better choice.
It has a .12 gauge shotgun barrel, and has six repeating shots. Famously used by the officers of the 22nd, 26th, 28th, and 59th Maine. Three generals in the Dixieland Army used it as well like J.E.B. Stuart and Pickett for a long time. On the Union the only man that loved the revolver as much as the Rebels did, was Buford and his cavalry brigade.
(Just a suggestion, but I'm kind of upset that you're using that. : \ )