The Type 1936A was becoming a better platform for 127 mm guns when the move to 15 cm, or 5.9-inch, weapons imposed a new set of demands. These were cruiser guns on hulls still much smaller than cruisers, despite the destroyers' substantial displacement. Improving stability enough for the earlier guns did not provide an equally satisfactory platform for the heavier weapons. The larger shells also took longer and more effort to move and load on a rolling, maneuvering deck. The guns offered a useful increase in firepower, but the firm judgment is that their handling demands made them unsuitable for these destroyers.
Notable Point · 56:49-59:58
Why 5.9-inch guns overburdened the Type 1936A
The 15 cm battery increased firepower while worsening the demands on aiming, loading and shell handling aboard a destroyer.