Why choose a 5.5-inch gun over a 6-inch gun?

Why use 5.5-inch guns rather than 6-inch guns on this escort cruiser?

The lighter 5.5-inch weapon retains useful operational capability with a trained crew, avoids some handling and stabilization penalties, and occupies a different practical niche from a 6-inch cruiser gun.

The 5.5-inch gun is lighter than the 6-inch alternative, and Britain historically came close to adopting it as a standard weapon. The comparison places 6 inches near the upper limit for practical manual handling and 5.9 inches near the lower limit for a cruiser gun. At 5.5 inches, handling becomes easier, and a well-trained crew can approach the operational capability of 4.5- or 4.7-inch weapons while managing stabilization. Calibre choice therefore follows crew workload and role as well as projectile size.