6-inch/50-caliber gun

6"/50 caliber Mark 6 and Mark 8
USS Ohio (BB-12), 6-inch/50 caliber guns.
Type	Naval gun Coastal defence
Place of origin	United States
Service history
In service	1903
Used by	United States Navy
Wars	World War I World War II
Production history
Designer	Bureau of Ordnance
Designed	1898
Manufacturer	U.S. Naval Gun Factory Midvale Steel
Produced	1900–1917
No. built	Mark 6: 136 (Nos. 197, 210–259, 277–359, 421–422) Mark 8: 215 (Nos. 360–420, 427–510, 525–594)
Variants	Mark 6 and Mark 8
Specifications
Mass	18,112 lb (8,215 kg) (without breech) 18,628 lb (8,450 kg) (with breech)
Length	300.2 in (7,630 mm)
Barrel length	294 in (7,500 mm) bore (49 calibers)

Shell	105 lb (48 kg) naval armor-piercing
Caliber	6 in (152 mm)
Elevation	−10° to +15°
Traverse	−100° to +100°
Rate of fire	6 rounds per minute
Muzzle velocity	2,800 ft/s (850 m/s)
Effective firing range	15,000 yd (14,000 m) at 14.9° elevation WWI charge 16,000 yd (15,000 m) at 15° elevation WWII charge

The 6"/50 caliber gun Mark 6 and Mark 8 (spoken "six-inch-fifty-caliber") were used for the secondary batteries of the United States Navy's Maine-class and Virginia-class battleships, as well as the Pennsylvania-class and Tennessee-class armored cruisers. They were also used as the main battery on the St. Louis-class protected cruisers.