I split my ammo 60/40 between HE and AA shells and I run out of at least one if not both types every game when playing my US DD IV Fletcher .

This wasn't as big a problem when using the single 5" guns but when switching to the dual 3" I could blow through all 400 shells in under 2 min if I fired non stop.

Suggestions would be either add researchable ammo expansion or since 3" shells are physically smaller then 5" shells in real life have any ship that upgrades from single larger caliber to double smaller caliber guns get a 25% increase in shell holding capacity.