Why Dora railway guns cannot arm Bismarck

What if Bismarck carried Schwerer Gustav or Dora guns in single turrets?

The mounting, recoil and loading arrangements exceed Bismarck's capacity; the proposed installation would need a much larger ship.

The railway gun's mount cannot simply be transferred into a turret on Bismarck. Rotation, loading arrangements and recoil handling would require a ship many times her size. Firing it from the proposed installation risks destructive structural loads. Its accuracy is disputed, while its barrel life is described as only tens of rounds. These drawbacks offer little compensation for the scale of the installation required.