Why heavy shells can fail during frantic loading

Why might shells have exploded in Bismarck's gun barrels during the final battle?

No single theory is established, but rushed loading, misalignment, fuze settings, or storage problems could cause premature detonation.

The answer does not claim a single proven explanation for shell failures during Bismarck's final action. Under extreme pressure, ammunition may be loaded too quickly, misaligned in the bore, incorrectly set, or affected by storage and handling problems. A heavy shell appears robust but contains components and explosive arrangements that require careful treatment. A later answer notes that small ball bearings may form part of the detonator mechanism, illustrating the delicate components hidden inside the projectile. That delicacy helps explain the slow adoption of automatic loading, because early machinery had to prove it could handle ammunition without striking or misaligning it. The discussion turns a dramatic failure into a broader engineering lesson: the strongest-looking objects in a weapon system can impose some of its most exacting handling requirements.