BL 4.7 inch /45 naval gun

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BL 4.7-inch (120 mm), 45-calibre naval gun
HMAS Stuart A 4.7 inch gun.jpg
"A" gun on destroyer HMAS Stuart, circa. 1930s
Type Naval gun
Service history
In service 1918–45
Used by  United Kingdom
Wars World War I World War II
Production history
Designed Mk I: 1918
Mk II: 1940[1]
Produced Mk I: 1919
Mk II: 1940[2]
No. built Mk I: 187
Mk II: 32[3]
Variants Mk I, Mk II[note 1]
Specifications
Weight Mk I: 7,000 pounds (3,200 kg)
Mk II: 7,028 pounds (3,188 kg)[4]
Barrel length 213 inches (5.4 m) bore (45 calibres)

Shell 50 pounds (22.7 kg)[5]
Calibre 4.724 inches (120 mm)
Elevation -9.5° to +30°[6]
Traverse -120° to +120°[7]
Rate of fire 5-6 RPM[8]
Muzzle velocity 2,670 feet per second (814 m/s)[9]
Maximum firing range 15,800 yards (14,450 m) at 30°[10]

The BL 4.7-inch, 45-calibre gun (actually a metric 120 mm gun) was a British medium-velocity naval gun introduced in 1918 for destroyers, intended to counter a new generation of heavily armed destroyers that Germany was believed to be developing.

Description and History[edit]

Gunners on destroyer HMS Broke, September 1940
On a Landing Craft Gun (L), preparing for the Invasion of Normandy, 1944

Mk I, of built-up wire-wound construction with propellant charge in a cloth bag went into service beginning in 1918 on destroyers of the new Admiralty type destroyer leader (Scott class) and Thornycroft type leader (Shakespeare class). Some saw service in World War I, but most entered service after the war ended.

It was also mounted on :

Mk II was a monobloc-barrel (i.e. single-piece, typical of small-medium World War II guns) gun of similar performance introduced in World War II to replace the worn-out Mk I guns on surviving ships.

These were the only BL-type 4.7-inch guns in British service, all others have been of the QF-type. They were superseded on new destroyers from 1930 by the 4.7 inch QF Mark IX.

Ammunition[edit]

See also[edit]

Weapons of comparable role, performance and era[edit]

Notes[edit]

  1. ^ Mk I = Mark 1, Mk II = Mark 2. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II, and used separate number series for BL and QF guns of the same calibre. Hence these were the first (and only) two models of British BL 4.7-inch guns.

References[edit]

  1. ^ DiGiulian
  2. ^ DiGiulian
  3. ^ DiGiulian
  4. ^ DiGiulian
  5. ^ DiGiulian
  6. ^ DiGiulian
  7. ^ DiGiulian
  8. ^ DiGiulian
  9. ^ Mk I : 814 m/s : http://navalhistory.flixco.info/H/72400x53535/8330/a0.htm
  10. ^ Mk I : 14450 metres : http://navalhistory.flixco.info/H/72400x53535/8330/a0.htm

Bibliography[edit]

External links[edit]