Worst comes to worst, you can always make some from some 45-70 brass... but other than trimming to size, you may have to turn the rim down from the 45-70's 0.608" to the 480's 0.540", turn the rim thickness down to 0.065" from the case side, you don't want to mess up the primer pocket depth. Once that's done trim case length to 1.285 and neck size to fit bullet 0.477", and load...
Phil