Enfield P53 conversion musket 1862 MYSTERY RIFLE 1853 percussion

This one is bizarre, and has me completely stumped. It appears to be a British Snider cartridge-conversion Enfield P53 which was subsequently converted BACK to a percussion muzzle loader by removing the cartridge block and setting the barrel back. 1862 Tower lock plate. Stock inlet for the Snider breech assembly and with a nice clear Birmingham stock cartouche. Bore is very nice, bright and sharp with moderate frosting throughout. Barrel measures 30” from muzzle to bolster clean out screw. I have never encountered a “reconversion” like this and the only circumstance I can think of where it'd be useful is in some sort of colonial environment where metallic ammunition was not readily available. Even then, one would think a supply of original percussion guns would be cheaply available. I don't think it was done with intent to deceive (no spurious “CSA” or other Confederate markings applied, etc). In any case, the work looks to have been performed a very long time ago. A very unusual and interesting musket that is worthy of further research to determine whether this was some type of “official” pattern.