See Gun Digest # 46, 1992, pages 50-56. There is an article by Ross Simpson, "Kangaroo Rifles Then And Now". He shows and mentions several small "roo" cartridges once used for those critters, among them .450 No.1 Carbine, .450 No.1, .425 Webley and .442 long, .430 long. All these small cartridges were replaced in Australian use by American repeaters in .44-40.