This US Navy training film covers the major caliber naval gun: its design requirements, construction, mounting, and the handling systems needed to load and fire multi-hundred-pound projectiles at high rates. The film explains why major caliber guns demand precision manufacturing to tolerances measured in thousandths of an inch, and how propellant charges and projectiles move through the handling system from magazine to breech.
The term "major caliber" in US Navy usage referred to guns of 6-inch bore and above. By the early 1950s the 16-inch/50 guns of the Iowa Class battleships represented the largest guns in the fleet — capable of hurling a 2,700-pound armor-piercing projectile more than 23 miles.
See also: Major Caliber 16″/50 Guns and Turrets — 1955 Training Video and Main Battery Fire Control. Part of the US Navy Films from the 1950s series.