What practical calibre breakpoints appear as naval guns move from manual to mechanical loading?
Short answerRoughly 6 inches for manual loading and 9.2 inches for rapid mechanical loading, with still larger guns trading progressively more firing speed for power.
NotesNaval-gun calibre follows a series of handling thresholds rather than a smooth scale. Around 6 inches lies the upper practical edge of manual loading. About 9.2 inches is the largest calibre associated with genuinely rapid mechanical loading, while the range just above it gives up speed without yet delivering capital-ship effect. Beyond roughly 16.5 inches the realistic rate of fire falls further, and at extreme calibres near 21 inches the firing loads threaten the gun's own machinery.