The 5-inch /54-caliber (Mk 45) lightweight gun is a U.S. naval artillery gun mount consisting of a 5 in L54 Mark 19 gun on the Mark 45 mount. It was designed and built by United Defense, a company later acquired by BAE Systems Land & Armaments, which continued manufacture. The latest 62-calibre-long version consists of a longer-barrel L62 Mark 36 gun fitted on the same Mark 45 mount. The gun is designed for use against surface warships, anti-aircraft and shore bombardment to support amphibious.
