Would a very high-rate 40-millimeter naval gun be better as a Gatling or a single-barrel weapon?
Short answerA Gatling layout, because multiple barrels share heat and wear and can cool between shots.
NotesA Gatling arrangement is preferable to a single-barrel Bofors-style system for a very high-rate 40-millimeter weapon. The decisive concern is barrel wear. Rotating among several barrels gives each tube more time to cool and distributes erosion across the set. That makes sustained fire easier to manage and protects the weapon's useful life. Practical rate of fire is constrained by these less visible engineering limits.