Specifications 60weight (tn) 127caliber (mm) 40Rate of fire (round/min) Used by 1960 Akizuki class destroyer DD 31960 Charles F. Adams class guided-missile destroyer DDG 21964 Belknap class guided-missile cruiser CG 11965 Knox class frigate FF 11967 Takatsuki class destroyer DD 21973 Haruna class helicopter carrier H 21973 Baleares class guided-missile frigate FFG 11976 Tachikaze class guided-missile destroyer DDG 21986 Hatakaze class guided-missile destroyer DDG 2 In Service Hellenic Navy US Navy Japanese Navy Mexican Navy Turkish Navy Egyptian Navy Spanish Navy