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.
== Description == These wire-wound built-up guns had originally been planned for the cancelled G3-class battlecruiser design upon which the Nelson class drew. Sir W. G. Armstrong Whitworth & Company at Elswick, Vickers at Barrow-in-Furness, William Beardmore & Company at Dalmuir and the Royal Gun Factory at Woolwich made a total of 29 guns of which 18 would be required for both ships at any time.
These guns broke with the example offered by the earlier 15-inch Mk I gun, which fired a heavy shell at a rather low muzzle velocity and instead fired a rather light shell at a high muzzle velocity; this was not a success, as at that muzzle velocity the gun wore rapidly and the accuracy was unsatisfactory, so much that it was lowered. A heavier shell was proposed but not adopted because of stringent budget policies of the 1930s; this naval gun was not seen as much of a success.
== Successor == An improved weapon, the BL 16-inch Mark II was designed for the Lion-class battleship which was a successor to the King George V class taking advantage of the larger weapon allowed under the London Naval Treaty from March 1938. This "new design" of 16-inch gun fired a shell that weighed 2,375 pounds (1,077 kg). Construction of first two Lion-class battleships - each of which was to have nine 16-inch guns - was halted at the start of the Second World War; only a few months after they were laid down. Work on the armament continued for a while but that was also stopped after only four guns and no turrets were produced.
See also
=== Weapons of comparable role, performance and era === 41 cm/45 3rd Year Type naval gun: Japanese equivalent 16"/45 caliber Mk 1, 5 & 8 gun: American equivalent
Notes
== References == Brown, David K. (2006). Nelson to Vanguard: Warship Design and Development 1923-1945. London: Chatham Publishing. ISBN 1-59114-602-X. Campbell, John (1985). Naval Weapons of World War II. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-459-4.
External links
Tony DiGiulian, British 16"/45 (40.6 cm) Mark I