6-inch/40-caliber gun

6"/40 caliber Mark 4
USS Massachusetts (BB-2), 6-inch/40 caliber gun and crew.
TypeNaval gun
Place of originUnited States
Service history
In service1885
Used byUnited States Navy
Wars
Production history
DesignerBureau of Ordnance
Designed1883
ManufacturerU.S. Naval Gun Factory
Produced1896 – 1905
No. built72 (Nos. 133–196, 260–263, and 423–426)
VariantsMark 4 Mod 0 – Mod 13 (no Mod 6)
Specifications
Mass13,370 lb (6,060 kg) (without breech)
Length
  • Mod 0: 256.1 in (6,500 mm)
  • Mod 1: 254.61 in (6,467 mm)
Barrel length240 in (6,100 mm) bore (40 calibers)

Shell105 lb (48 kg) naval armor-piercing
Caliber6 in (152 mm)
Traverse−150° to +150°
Rate of fire
  • As commissioned: 1.5 rounds per minute
  • After 1906: 7.6 rounds per minute
Muzzle velocity2,150 ft/s (660 m/s)
Effective firing range
  • 9,000 yd (8,200 m) at 15.3° elevation
  • 18,000 yd (16,000 m) at 30.2° elevation

The 6"/40 caliber gun Mark 4 (spoken "six-inch-forty-caliber") were used for the secondary batteries of the United States Navy's Indiana-class and Illinois-class battleships. They were also used as the main battery on the Cincinnati-class protected cruisers.[1][2]