Why larger naval guns may return

Are functional railguns or the return of large-caliber naval guns more likely?

The initial answer favors functional railguns, while also predicting renewed interest in larger conventional guns for greater shell weight and range.

The initial answer favors functional railguns and suggests that roughly 9.2 inches could prove a useful calibre. This is a prediction about development, without a demonstrated working system presented here. Conventional guns could also grow as navies seek heavier shells and longer range, with 6-inch and some 8-inch mounts proposed for surface combatants of roughly 6,000 tons or more. Those ships are cruiser-sized even when called destroyers. A later return to the calibre question notes that a modern 5-inch gun already reaches about twenty-five miles, a range once associated with larger naval weapons. The ammunition debate also asks how to combine greater reach with the gun's ability to carry many inexpensive rounds.