16"/45 caliber Mark 6 guns
... that the 16"/45 caliber Mark 6 guns aboard the battleship USS Massachusetts (BB-59) are believed to have fired the United States' first and last 16-inch shells of World War II?
... that the <b id="mwB84"><a class="mw-redirect" href='./16"/45_caliber_Mark_6_gun' id="mwB88" rel="mw:WikiLink" title='16"/45 caliber Mark 6 gun'>16"/45 caliber Mark 6 guns</a></b> aboard the battleship <a about="#mwt29" data-mw='{"parts":[{"template":{"target":{"wt":"USS","href":"./Template:USS"},"params":{"1":{"wt":"Massachusetts"},"2":{"wt":"BB-59"}},"i":0}}]}' href="./USS_Massachusetts_(BB-59)" id="mwB9A" rel="mw:WikiLink" title="USS Massachusetts (BB-59)" typeof="mw:Transclusion">USS<span typeof="mw:Entity"> </span><i>Massachusetts</i><span typeof="mw:Entity"> </span><span class="nowrap">(BB-59)</span></a> are believed to have fired the United States' first and last 16-inch shells of <a href="./World_War_II" id="mwB9E" rel="mw:WikiLink" title="World War II">World War II</a>?