Why a 10-inch cruiser gun falls between useful categories

Could a 10-inch gun have been a viable cruiser weapon in the 1920s?

Probably not, because 9.2-inch guns offered a better rate of fire while 12-inch guns delivered much greater power at a similar firing rate.

The 10-inch gun occupies an awkward middle ground for a large cruiser. Its rate of fire approaches that of a 12-inch weapon, but the larger shell is much more powerful. A 9.2-inch gun can fire faster and may fit economically into triple turrets. Without treaty limits, designers would probably choose 6-inch guns for scouts, 9.2-inch weapons for intermediate cruisers, and 12-inch guns for the heaviest type rather than settle on ten inches.