BL 5.5-inch Mk I naval gun
| BL 5.5-inch Mark I | |
|---|---|
| Type | Naval gun, Coastal defence |
| Place of origin | United Kingdom |
| Service history | |
| In service | 1913–1954 |
| Wars | World War I World War II |
| Production history | |
| Designer | Coventry Ordnance Works |
| Designed | 1913 |
| Manufacturer | Coventry Ordnance Works |
| No. built | 81 |
| Specifications | |
| Mass | 13,955 lbs (6,330 kg) |
| Length | 275 inches (7.0 m) L/50 |
| Shell | 82 pounds (37.19 kg) |
| Calibre | 5.5-inch (140 mm) |
| Breech | Welin breech block with Holmstrom mechanism |
| Elevation | -7 degrees to +30 degrees depending on mount |
| Rate of fire | 12 rounds per minute |
| Muzzle velocity | 2,790 f/s (850 m/s) |
| Effective firing range | 17,800 yards (16,300 m) at 30-degree elevation |
The Breech Loading 5.5-inch Mk I was a naval gun used by the British Royal Navy during both World Wars.