At 45 degrees of elevation, the 5.25-inch gun's stated range with a high-explosive shell was 23,400 yards, compared with about 25,000 yards for the 6-inch gun. Expected cruiser engagements at roughly 18,000 to 21,000 yards therefore put the smaller weapon within useful fighting range. Its sustained rate of seven to eight rounds per minute also compared favorably with the six to eight rounds, usually six, given for the larger gun. That combination made the Didos dangerous to lightly protected cruisers and smaller attacking ships. Against a heavy cruiser, disabling its fighting ability long enough to permit torpedo attack was a more plausible objective than destruction by gunfire alone.
Notable Point · 1:09:16-1:11:28
Why the 5.25-inch gun reached useful cruiser fighting ranges
The 5.25-inch battery combined useful cruiser engagement range with sustained fire comparable to or slightly faster than the larger 6-inch gun.