Gun Overhaul and Upgrade NavWeaps.Com: 5"/54 (12.7 cm) Mark 45 Mods 0 – 2 NavWeaps.Com: 5"/62 (12.7 cm) Mark 45 Mod 4 FAS: Gunner officer information sheet 127 mm artillery 5 inch Naval guns of the United States Naval weapons of the Cold War Military equipment introduced in the 1970s