| Ordnance BL 16 inch Mark I | |
|---|---|
 Guns of HMS Rodney at maximum elevation, 1940 | |
| Type | Naval Gun |
| Place of origin | UK |
| Service history | |
| In service | 1927–1948 |
| Used by | UK |
| Production history | |
| Designed | 1922 |
| Specifications | |
| Mass | 108 tons (109.7 tonnes) |
| Length | 61 ft 10 in (18.85 m) |
| Barrel length | 60 ft (18.3 m) L/45 |
| Shell | separate charge, AP shell |
| Shell weight | 2,048 pounds (929 kg) |
| Calibre | 16 inch (406 mm) |
| Breech | Welin |
| Elevation | 40°/-3° in mounting Mark I |
| Rate of fire | 2 rounds per minute as fitted |
| Muzzle velocity | 2,586 feet/second (788 m/s) |
| Effective firing range | 35,000 yards (32,000 m) at 32° elevation |
| Maximum firing range | 39,780 yards (36,375 m) |
The BL 16-inch Mark I was a British naval gun introduced in the 1920s and used on the two Nelson-class battleships. A breech-loading gun, the barrel was 45 calibres long ("/45" in shorthand) meaning 45 times the 16-inch (406 mm) bore – 60 ft (18 m) long.