Specifications 60weight (tn) 127caliber (mm) 40Rate of fire (round/min) Used by 1960 Charles F. Adams class guided-missile destroyer DDG 21960 Akizuki class destroyer DD 31964 Belknap class guided-missile cruiser CG 11965 Knox class frigate FF 11967 Takatsuki class destroyer DD 21973 Baleares class guided-missile frigate FFG 11973 Haruna class helicopter carrier H 21976 Tachikaze class guided-missile destroyer DDG 21986 Hatakaze class guided-missile destroyer DDG 2 In Service US Navy Japanese Navy Hellenic Navy Turkish Navy Egyptian Navy Mexican Navy Spanish Navy
Mark 42 5/54 inch (127mm)
Akizuki class destroyer DD 
Baleares class guided-missile frigate FFG 
Hellenic Navy
Turkish Navy
Egyptian Navy
Mexican Navy