8-inch/45-caliber gun

8"/45 caliber Mark 6
8"/45 caliber Mark 6
	Admiral Montgomery M. Taylor, Commander-in-Chief of the U.S Navy Asiatic Fleet, and his fleet staff aboard the USS Rochester (CA-2) at Shanghai, China, in 1932. Front row (left to right): Captain Montgomery E. Higgins, M.C.; Captain Ivan E. Bass; Captain Frank J. Fletcher; Admiral Montgomery M. Taylor; Commander Donald B. Beary; Captain Jeffrey F. Kutz, S.C.; and Colonel Jeffrey F. Dyer, U.S. Marine Corps. Back row (not in order): Lieutenant Henri H. Smith-Hutton; Lieutenant Commander Charles A. MacGowan; Lieutenant Commander Philip W. Warren; Lieutenant Commander Francis T. Spellman; and Lieutenant Junior Grade Royal Lovell. Other officers are unidentified. United States Navy Historical Photo #: NH 83799
Type	Naval gun; Coastal artillery; Railway gun;
Place of origin	United States
Service history
In service	1906
Used by	United States Navy; United States Army; Hellenic Navy;
Wars	World War I; Greco-Turkish War; World War II;
Production history
Designer	Bureau of Ordnance
Designed	1900
Manufacturer	U.S. Naval Gun Factory
No. built	148 (Nos. 108–255)
Variants	Mark 6 Mod 1 – Mod 4
Specifications
Mass	41,518 lb (18,832 kg) (without breech); 41,988 lb (19,045 kg) (with breech);
Length	30 ft 9 in (9.37 m)
Barrel length	30 ft 0 in (9.14 m) bore (45 calibers)
Shell	260 lb (120 kg) naval armor-piercing; 260 lb (120 kg) army AP Mark 20; 240 lb (110 kg) army high-explosive M103;
Caliber	8 in (203 mm)
Recoil	28.5 in (720 mm) max
Elevation	Marks 12: −7° to +20°; Marks 5: −7° to +20°; M1A1: −0° to +45°;
Traverse	−135° to +135° naval mounts; 360° army M1A1 mount;
Rate of fire	1 to 2 rounds per minute
Muzzle velocity	2,750 ft/s (840 m/s) naval AP; 2,100 ft/s (640 m/s) army AP; 2,750 ft/s (840 m/s) army AP (super charge); 2,150 ft/s (660 m/s) army HE; 2,840 ft/s (870 m/s) army HE (super charge);
Effective firing range	22,500 yd (20,574 m) at 20.1° elevation; 35,300 yd (32,278 m) at 45° elevation (Army RR gun);

The 8"/45 caliber Mark 6 gun (spoken "eight-inch-forty-five--caliber") were used for the secondary batteries of the United States Navy's last pre-dreadnought battleships and refitted in older armored cruisers main batteries.

8"/45 caliber Mark 6
Admiral Montgomery M. Taylor, Commander-in-Chief of the U.S Navy Asiatic Fleet, and his fleet staff aboard the USS Rochester (CA-2) at Shanghai, China, in 1932. Front row (left to right): Captain Montgomery E. Higgins, M.C.; Captain Ivan E. Bass; Captain Frank J. Fletcher; Admiral Montgomery M. Taylor; Commander Donald B. Beary; Captain Jeffrey F. Kutz, S.C.; and Colonel Jeffrey F. Dyer, U.S. Marine Corps. Back row (not in order): Lieutenant Henri H. Smith-Hutton; Lieutenant Commander Charles A. MacGowan; Lieutenant Commander Philip W. Warren; Lieutenant Commander Francis T. Spellman; and Lieutenant Junior Grade Royal Lovell. Other officers are unidentified. United States Navy Historical Photo #: NH 83799
Type	Naval gun Coastal artillery Railway gun
Place of origin	United States
Service history
In service	1906
Used by	United States Navy United States Army Hellenic Navy
Wars	World War I Greco-Turkish War World War II
Production history
Designer	Bureau of Ordnance
Designed	1900
Manufacturer	U.S. Naval Gun Factory
No. built	148 (Nos. 108–255)
Variants	Mark 6 Mod 1 – Mod 4
Specifications
Mass	41,518 lb (18,832 kg) (without breech) 41,988 lb (19,045 kg) (with breech)
Length	30 ft 9 in (9.37 m)
Barrel length	30 ft 0 in (9.14 m) bore (45 calibers)

Shell	260 lb (120 kg) naval armor-piercing 260 lb (120 kg) army AP Mark 20 240 lb (110 kg) army high-explosive M103
Caliber	8 in (203 mm)
Recoil	28.5 in (720 mm) max
Elevation	Marks 12: −7° to +20° Marks 5: −7° to +20° M1A1: −0° to +45°
Traverse	−135° to +135° naval mounts 360° army M1A1 mount
Rate of fire	1 to 2 rounds per minute
Muzzle velocity	2,750 ft/s (840 m/s) naval AP 2,100 ft/s (640 m/s) army AP 2,750 ft/s (840 m/s) army AP (super charge) 2,150 ft/s (660 m/s) army HE 2,840 ft/s (870 m/s) army HE (super charge)
Effective firing range	22,500 yd (20,574 m) at 20.1° elevation 35,300 yd (32,278 m) at 45° elevation (Army RR gun)