Corrected entry: As USS Cassidy is breaking out of Pearl Harbor, the ship's captain and XO are chasing her in a launch. The view of the launch from the bridge is interrupted by a twin 5"38 mount rotating back and forth. Unfortunately, every other view of the USS Cassidy reveals that her stern mount is a single 5-incher.
goofyfoot
7th Feb 2014
Correction: This in incorrect. All guns seen in this shot are also seen prior to her getting underway in Pearl Harbor. There is a 5" single gun mount at the stern, but there is also a twin, open mount between the rear turret and the bridge and that is what is seen traversing through the shot.