This is a US Navy training video from 1955 describing the operation of the 16″/50 gun and turret. It took 79 men to operate the turret and its three guns.
From the armored gun house at the top, down through the rotating structure and barbette, the film uses cross sections and detailed descriptions of each component to take you inside the turret and show how these guns — carried by the Iowa Class battleships — actually operate.
All aspects are shown: loading the powder, handling the 2,500-plus-pound projectiles, and fire control.