The 5"54 MK 42 MOD 10 fires a 5-inch shell that measure approximately
127mm in diameter. It consists of two component groups: the lower
structure (below deck) and the upper structure (above deck). Lower
structure components include the carrier, lower hoist and ammunition
loader drums.
These components provide an uninterrupted flow of
ammunition. The upper structure components include the upper hoist,
transfer trays, rammer and the components used to fire the gun. They
also aim the gun and eject the empty powder cases from the gun.