What is the largest gun caliber likely to appear on future Russian and other warships?
Short answerAbout 6 inches is plausible, as Zumwalt already demonstrates, but routine adoption of larger naval guns is unlikely.
NotesThe discussion points to Zumwalt's 155 mm Advanced Gun System as proof that modern warships have already returned to approximately 6-inch caliber. Larger weapons remain technically possible, and OTO Melara has explored 8-inch concepts. The panel nevertheless treats 6 inches as the likely practical ceiling for general future service. The watch point frames caliber as a balance among payload, range, ship size, and the availability of missile alternatives rather than a simple return to battleship-era guns.