According to Labbett, p. 79, some of the Mk. 2 ammunition was found to have weak heads causing jams in some of the Gardner machine guns. As a result the ‘CARTRIDGE MACHINE GUN BALL .45 inch MARK 3 (GARDNER, GATLING AND NORDENFELT EXCEPT MH (MARTINI HENRY) CHAMBERED GUNS)’ was approved in 1886. These had thicker case walls than the Mk. 2 but with the same 63mm case length.