In 1895, W.W. Greener invented the world's first Humane Killer, a gun designed to kill cattle, sheep, pigs and horses, quickly and easily. This instrument was adopted by the War Office, for use in the Veterinary, Remount and Butchering Departments, and by the Admiralty for its Victualling yards. The instrument was also modified to use .310 caliber cartridges. After several years, the models became obsolete in the 1960s and ammunition for the older models was impossible to obtain. Recently though, the company was asked to manufacture another model and hence, the Humane Killer Mk II was introduced. This new gun fires a .32 ACP round.