A 40 mm quad mount on a U.S. Navy heavy cruiser off Korea, in 1950.
U.S. Navy
<a rel="nofollow" class="external text" href="http://www.navy.mil/ah_online/department_arch.html">U.S. Navy All Hands magazine</a> <a rel="nofollow" class="external text" href="http://www.navy.mil/ah_online/archpdf/ah195009.pdf">September 1950</a>, cover.