Back Canon de marine de 4,7 pouces BL Mk I & II French BL 4,7″/45 Russian 120-мм морська гармата BL 4.7 inch /45 Ukrainian
| BL 4.7-inch (120 mm), 45-calibre naval gun | |
|---|---|
 "A" gun on destroyer HMAS Stuart, circa. 1930s | |
| Type | Naval gun |
| Service history | |
| In service | 1919–1948 |
| Used by | United Kingdom |
| Wars | 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 | |
| Mass | 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) |
| Breech | Welin breech block |
| 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.
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