Why 9.2-inch guns hit harder in shore bombardment

What is the practical difference between 8-inch and 9.2-inch guns for shore bombardment?

The 9.2-inch shell carries significantly more explosive, so comparable rates of fire deliver much more destructive weight over time.

A 9.2-inch shell carries a larger explosive charge than the 8-inch shell used in this comparison. The figures given are a 380-pound, roughly 172.5-kilogram projectile containing 16.1 kilograms of explosive, against about 10 kilograms of explosive in the 8-inch shell. That gives the larger round approximately six additional kilograms of explosive. At an assumed equal rate of six rounds per minute, nine guns would deliver roughly 0.3 tonnes more explosive each minute. Sustained fire compounds the difference, although the calculation depends on the selected ammunition and assumed firing rate.