I may wind up regretting these words... but in my opinion, it sure looks like a modernday "fabrication." In other words, some modernday guy jammed a dug hard-rammed Williams "Cleaner" bullet into a brass casing which does not look like a dug casing.
I should mention in case there are any readers here who don't already know... cartridge-bullets do not get rammed down the muzzle of a gun. Sure seems like a ramrod-mark on that .58 bullet's nose.
Regards,
Pete