Help ID this muzzleloader pistol

I need some help IDing this percussion cap ML pistol. My grandfather was a civil war buff and in the 60s and 70s he searched fields and found Minnie balls and round balls from Antietam battlefields. He also had this pistol in his stash of Civil war items. I started disassembly of it yesterday but found no markings other than some rust faded engraving. This is a replica because the the screws and springs are "Modern". The barrel measured .367 inches. I want to find a new cap nipple at a minimum and a new flame tunnel (The piece that the nipple screws into.) Most of my searches come back with the Colt 36 caliber revolvers and I'm stumped.

Thanks guys. One of the first thing I noticed was that the stock had scorch marks inside. Turns out the handle/tang which is the screw in kind did not 100% seal so with each shot it had dumped some pressure into the stock area. I did get the drum and nipple seperated quite easily. The barrel is in great shape, just surface rust. Its going to work with me tomorrow to get alox blasted. Then Ill either go Ultra Blak 400 or Duracoat Durablue. No issues with never firing it again but it is a cool piece but I need to do something to protect it.