I have a couple of comments about the Burnside: I have shot several originals using the brass cartridges sold by Dixie Gun Works some years ago. I had zero leakage at the breach, and when the breach was opened smartly, not only did the cartridge case pop partially up, so you could grasp it easily and remove, but as the action is opened, a projection on the rear of the receive hits the wings on the fired cap, kicking it off the cone! Mine was also a Fifth Model or Fourth Model, Second Type, depending on collector's terminology, (with the guide screw in the right side of the receiver that guides the block. IMHO, I would have preferred the Burnside in CW combat, to the Sharps, as the Sharps' cone would foul eventually, losing its effectiveness in sealing the breach. Of course, I would prefer the Spencer to either due to its self-contained cartridge.