 Short-range air defence was provided by 73 Bofors 40 mm AA guns in a variety of mountings. Vanguard had ten sextuple-barrel power-operated mounts concentrated in the superstructure and stern, a twin-barrel mount on 'B' turret, and 11 power-operated single mounts on the upper deck and rear superstructure. All mounts could depress to − 10°and elevate to a maximum of + 90 °. The 40-millimetre (1.6 in) gun fired a 1.97-pound (0.89 kg) shell at a muzzle velocity of 2,890 ft / s (880 m / s) to a distance of 10,750 yards (9,830 m). The gun's rate of fire was approximately 120 rounds per minute. Space was not available to stow the standard allowance of 1564 rounds per gun, and Vanguard only carried 1269 rounds per gun. Two of the single guns on the quarterdeck were removed in 1949 and five others during a major refit in 1954. All of her multiple Bofors mounts were removed at this same time.
