The loaded cartridge is a .43 Spanish. The spent one is an 11MM Mauser.
The barrel stub is a handy "Comparator",.....welded shut at the muzzle, so's not to freak out the regulators.
GTC
Member, Clan of the Border Rats -- “Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it.”- Mark Twain
the regulators.