Why Britain chose 5.25-inch instead of 5.5-inch guns

Why did the Royal Navy adopt the 5.25-inch gun instead of the 5.5-inch?

A perceived rate-of-fire advantage favoured 5.25-inch, while greater mechanisation added weight under treaty limits. The size of the practical advantage is questioned.

The 5.5-inch gun receives a favourable assessment despite Britain's later choice of 5.25-inch. Politics is one proposed explanation, although the particular decisions remain unspecified. A perceived rate-of-fire advantage for the smaller ammunition also influenced the choice, with doubt expressed about the size of that advantage in practice. Even a small change in calibre affects the weight repeatedly handled by a crew. More mechanisation could support faster handling, but would add mounting weight under treaty limits.