Most people think about the Remington Rolling Block as a purpose-built rifle, but it was also used as a way to transform muzzleloaders into more modern breechloaders. Remington did this commercially, and small gunsmiths did it as well. Essentially any old rifle could contribute a barrel, stock, and furniture – just add a Remington action and you can have a cartridge-firing rifle for much less that the cost of getting one brand new.
The Rolling Block transformation we are looking at today appears to have been built on a Confederate Gillam & Miller rifle – an extremely rare pattern. Gillem & Miller only managed to produce 677 rifles for the state of North Carolina during the Civil War, and only a handful of intact surviving examples are known. This one shows what was typical of usable arms in the post-war South – they were used hard, and updated when feasible to keep them useful.