Why 4.5-inch destroyer mounts took time

Why did the 4.5-inch gun mount take so long to develop?

The gun came relatively quickly; stable destroyer mounts, especially twin mounts, were the difficult part.

Development of the 4.5-inch gun is separated from development of the machinery that carried it. Mountings for capital ships and carriers were available early enough to shape 1930s construction and reconstruction work. Destroyers imposed a different integration problem because a smaller hull had to carry and control the weapon without unacceptable instability. The twin destroyer mounting therefore took longer even though the underlying gun had arrived comparatively quickly.