User blog comment:FlammeumDraco333/Tales From the Not so Blocky Seas/@comment-25584152-20150630165315/@comment-10905876-20150630170117

Dual 5". Secondary weapons need a good rate of fire, and the single 6" doesn't provide that as well as the dual 5". You may get better range and damage with the single 6", but getting off more shots between main battery shots is usually the goal. And a steady stream of 5" fire is very effective against those pesky destroyers.