Royal Navy trials valued the total weight of explosive delivered and the likelihood of scoring damaging hits, not merely the power of one shell. An individual 8-inch projectile was more destructive, but a 6-inch gun could create more chances to hit or blind an opponent before a torpedo attack. The 6-inch round also sat near the upper limit that one person could move repeatedly through a quick-firing cycle. Above that size, machinery or several handlers became necessary and slowed the process. The caliber's importance therefore came from the interaction of shell effect, hit probability, and sustainable human handling.
Notable Point · 16:07-17:34
Six inches marks the practical hand-loading ceiling
The six-inch gun became dominant because its shell was near the upper limit that one person could handle quickly and repeatedly.