BL 6 inch gun Mk I - VI
Encyclopedia
The BL 6 inch guns Marks II, III, IV and VI were the second and subsequent generations of British 6-inch breechloading naval guns, designed by the Royal Gun Factory following the first 6-inch breechloader, the relatively unsuccessful BL 6 inch 80 pounder gun
designed by Elswick Ordnance. They were originally designed to use the old gunpowder propellants. They were superseded on new warships by the QF 6 inch gun from 1891.
and introduced a 100-pound projectile, which became standard for British 6-inch guns until 1930. It consisted of a much thicker steel barrel with wrought-iron jackets shrunk over it and as originally introduced weighed 81 cwt (9072 pounds). The gun proved to be too weakly constructed, and 5 steel chase hoops were added to strengthen it and the gun was shorted by 12 inches to rebalance it, resulting in a bore length of 144 inches (24 calibres) and final weight of 89 cwt (9968 pounds), or 4½ tons. These guns were relegated to non-firing drill use following a burst gun incident on HMS Cordelia in June 1891.
Mk IV incorporated the improvements to Mk III. Mk VI differed from Mk IV only in having slightly simplified construction.
Marks III, IV and VI became the most commonly deployed versions, and their widespread adoption would indicate they were considered successful. Marks III, IV and VI were interchangeable and had the same performance. They are generally referred to as "6-in 5-ton B.L.R." in contemporaneous publications such as Brassey's Naval Annual
.
Guns equipped the following British warships : and , laid down 1878 : Mk IIs laid down 1880s laid down 1881
and Vavasseur slides (inclined slides that absorbed recoil).
A small number of Mk IV and VI guns had their old 3-motion breeches replaced by modern single-motion types and the chamber lengthened to accept a more powerful cartridge, and became the BLC (breech loading converted) coast defence gun in 1902. They attained a maximum range of 12000 yards (10,972.8 m) using a 20 lb (9.1 kg) 15 oz cordite cartridge. They were replaced by the modern 6 inches (152.4 mm) Mk VII as they became available, and were declared obsolete in 1922.
and were then converted into 8-inch howitzers
.
Britain was desperately short of heavy field artillery at the beginning of World War I, and in 1915 old BL 6-inch guns were bored out and shortened to produce BL 8 inch howitzers
as follows :
BL 6 inch 80 pounder gun
The BL 6 inch 80 pounder gun Mk I was the first generation of British 6-inch breechloading naval gun after it switched from muzzle-loaders in 1880. They were originally designed to use the old gunpowder propellants.-Mk I 80-pounder:...
designed by Elswick Ordnance. They were originally designed to use the old gunpowder propellants. They were superseded on new warships by the QF 6 inch gun from 1891.
Development history
These were Royal Gun Factory designs, although they were also manufactured by Elswick Ordnance.Mark II
Mk II followed the early weakly made and less powerful Mark I 80-pounderBL 6 inch 80 pounder gun
The BL 6 inch 80 pounder gun Mk I was the first generation of British 6-inch breechloading naval gun after it switched from muzzle-loaders in 1880. They were originally designed to use the old gunpowder propellants.-Mk I 80-pounder:...
and introduced a 100-pound projectile, which became standard for British 6-inch guns until 1930. It consisted of a much thicker steel barrel with wrought-iron jackets shrunk over it and as originally introduced weighed 81 cwt (9072 pounds). The gun proved to be too weakly constructed, and 5 steel chase hoops were added to strengthen it and the gun was shorted by 12 inches to rebalance it, resulting in a bore length of 144 inches (24 calibres) and final weight of 89 cwt (9968 pounds), or 4½ tons. These guns were relegated to non-firing drill use following a burst gun incident on HMS Cordelia in June 1891.
Marks III, IV, VI
Mark III finally introduced an all-steel construction, with a steel barrel and steel breech-piece and hoops shrunk over it, weighing 89 cwt (4½ tons). However, as originally introduced Mk III was still limited to weak charges and low muzzle velocity, and most guns were strengthened by being chase-hooped to allow a full powder charge of 48 lb gunpowder and muzzle velocity of 1,960 feet per second. This brought the gun weight up to 100 cwt (5 tons).Mk IV incorporated the improvements to Mk III. Mk VI differed from Mk IV only in having slightly simplified construction.
Marks III, IV and VI became the most commonly deployed versions, and their widespread adoption would indicate they were considered successful. Marks III, IV and VI were interchangeable and had the same performance. They are generally referred to as "6-in 5-ton B.L.R." in contemporaneous publications such as Brassey's Naval Annual
Brassey's Naval Annual
The Naval Annual was a book that sought to bring together a large amount of information on naval subjects, which had hitherto been obtainable only by consulting numerous publications and chiefly from foreign sources...
.
Guns equipped the following British warships : and , laid down 1878 : Mk IIs laid down 1880s laid down 1881
- Colossus-class battleshipsColossus class battleship (1882)The Colossus class battleships were ironclad warships, carrying their main armament in turrets, which served in the Victorian Royal Navy from 1882...
of 1882 - Leander-class cruisersLeander class cruiser (1882)The Leander Class were a four ship cruiser programme ordered by the Admiralty in 1880. The class comprised HMS Leander, HMS Phaëton, HMS Amphion and HMS Arethusa.-Genesis:...
of 1882 - HMS HotspurHMS Hotspur (1870)HMS Hotspur was a Victorian Royal Navy ironclad ram – a warship armed with guns but whose primary weapon was a ram.-Background:It had been recognised since the time of the Roman Empire or before that a ship, while it might carry weaponry, was itself a potent weapon if used as a missile...
as re-gunned in 1883 : Mk IIs laid down 1885 - Orlando-class armoured cruisersOrlando class cruiserThe Orlando-class was a seven ship class of Royal Navy armoured cruisers completed between 1888 and 1889.- Building Programme :On 2 December 1884, the Secretary to the Admiralty stated, "The present Board have been gradually developing, and, as I would venture to say, in an effective manner, our...
laid down 1885 - HMS BellerophonHMS Bellerophon (1865)HMS Bellerophon was a central battery ironclad built for the Royal Navy in the mid-1860s.-Design and description:In this ship, designed by Sir Edward Reed, the power-to-weight ratio was increased; the long rows of guns on the broadside were replaced by a small number of guns, centrally placed, of...
as re-gunned in 1885 - Mersey-class protected cruisers of 1885
- Conqueror-class ironclad turret shipsConqueror class battleshipThe Conqueror class battleships were ironclad warships which served in the Victorian Royal Navy, and whose main weapon was designed to be the Ram.The class consisted of two ships, and...
completed 1886 - 1888 : Mk IIs laid down 1887 - HMS RupertHMS Rupert (1872)HMS Rupert was a battleship of the Victorian Royal Navy, whose principal weapon was designed to be her ram.-Design:She was similar in design to , but unlike her carried a revolving turret similar to that carried in...
as re-gunned in 1887 - Archer-class torpedo cruisers, launched in 1888s as re-gunned in the 1880s : Mk II
QFC conversion
From 1895 many ships' guns were converted to QF to use the same brass cartridge case and charge as the modern QF 6 inch guns. They were designated QFC for "QF Converted", and the new Mark designation began at I over the old gun Mark e.g. I/IV was the first version of Mk IV gun converted to QFC, II/VI was the second version of Mk VI gun converted.Coast defence gun
Mk IV and VI guns were widely used in coast defence around the British Empire, both on hydro-pneumatic disappearing mountingsDisappearing gun
A disappearing gun is a type of heavy artillery for which the gun carriage enabled the gun to rotate backwards and down into a pit protected by a wall or a bunker after it was fired...
and Vavasseur slides (inclined slides that absorbed recoil).
A small number of Mk IV and VI guns had their old 3-motion breeches replaced by modern single-motion types and the chamber lengthened to accept a more powerful cartridge, and became the BLC (breech loading converted) coast defence gun in 1902. They attained a maximum range of 12000 yards (10,972.8 m) using a 20 lb (9.1 kg) 15 oz cordite cartridge. They were replaced by the modern 6 inches (152.4 mm) Mk VII as they became available, and were declared obsolete in 1922.
BLC Siege gun
Mk IV and VI BLC guns were also fitted out with wagons in 1902 to allow them to be transported as semi-mobile siege guns - the gun and siege platform were transported as separate loads, the siege platform was assembled at the firing site and the gun mounted on it. When World War I broke out in 1914, 2 batteries of these BLC siege guns were equipped with primitive wheeled gun carriages with traction engine wheels and sent to France as heavy field guns. They were towed by steam traction engines. They had limited recoil buffers and required chocks in front and behind the wheels when firing. These guns had a maximum range of 14,200 yards. They were soon replaced in action as guns in 1915 by the more modern 6 inch Mk VIIBL 6 inch Mk VII naval gun
The BL 6 inch Gun Mark VII was a British naval gun dating from 1899, which was mounted on a heavy traveling carriage in 1915 for British Army service to become one of the main heavy field guns in the First World War, and also served as one of the main coast defence guns throughout the British...
and were then converted into 8-inch howitzers
BL 8 inch Howitzer Mk 1 - 5
The BL 8-Inch Howitzer Mark I through to Mark V were a British improvisation developed early in the First World War to provide heavy artillery...
.
World War I conversion to 8 inch howitzer
BL 8 inch Howitzer Mk 1 - 5
The BL 8-Inch Howitzer Mark I through to Mark V were a British improvisation developed early in the First World War to provide heavy artillery...
as follows :
- 12 BLC guns Mk I/IV became 8-inch howitzer Mk I
- 6 BL Mk IV and VI guns became 8-inch Howitzer Mk II
- 6 BL MK IV and VI guns, but adapted for different carriage, became 8-inch howitzer Mk III
- 8 BLC Mk I/VI adapted for Mk IV carriage became 8-inch howitzer Mk IV
Mk V
Mk V was a longer (30-calibres, 183.5 inch bore) unrelated Elswick Ordnance export gun.Surviving examples
- 3 guns at Green Hill Fort, Thursday Island, in the Torres Strait : Mk IV Gun No 727 dated 1890; Mark VI Nos 838 & 839 dated 1892.
- Mk IV gun on disappearing carriage at Lei Yue Mun FortHong Kong Museum of Coastal DefenceThe Hong Kong Museum of Coastal Defence is a museum in Hong Kong, located in a former coastal defence fort overlooking the Lei Yue Mun channel, near Shau Kei Wan on Hong Kong Island. The fort was built by the British in 1887, intended to defend the eastern approaches to Victoria Harbour.The total...
, Hong Kong. - Mk IV gun No. 726 dated 1890 at Princess Royal Fortress, Albany, Western AustraliaAlbany, Western AustraliaAlbany is a port city in the Great Southern region of Western Australia, some 418 km SE of Perth, the state capital. As of 2009, Albany's population was estimated at 33,600, making it the 6th-largest city in the state....
External links
- Diagram of Mk V gun on Hydropneumatic disappearing mounting Mk IV (or actually Mk I ?) at Palmerston Forts Society website
- Diagram of Mk IV or VI gun on Barbette Mk I on Slide Mk I at Palmerston Forts Society website
- Diagram of Armstrong Mk V (?) gun on disappearing carriage