A report that working naval guns lacked compatible army ammunition points to the limits of calibre labels. A ship can support a larger and longer round because its mounting, handling rooms, and magazines are not constrained by a land vehicle's dimensions. Army ammunition must fit guns and transport systems designed to move over land. Naval ammunition can therefore use different cartridges, projectiles, and handling arrangements even when the nominal calibre is the same. Calibre alone is an unreliable guide to logistical interchangeability between services.
Notable Point · 3:01:38-3:02:12
Why equal-calibre army and naval guns may not share ammunition
An identical calibre does not guarantee common ammunition because vehicle-mounted army guns and shipboard weapons can be designed around different shell and cartridge lengths.