This page is a collection of early British 8" (20.3 cm) breech loader bag guns from the late 1800s. These guns shared common characteristics including weak design and few of them survived in active service after 1900. Guns were either 26 or 30 calibers long, with the longer guns having slightly higher muzzle velocities, otherwise there was little difference in their performance. Shells were 180 to 210 lbs. (82 to 95 kg). A proposal was made in 1898 to introduce a a new 8" (20.3 cm) gun using a 250 lbs. (113 kg) shell, but this would have been too heavy for a two man team to handle. This led to development of the 7.5" (19 cm) guns which used a 200 lbs. (90.7 kg) shell.
As detailed information for these guns is limited, rather than creating a page for each one, I have decided to combine them into a single page.
It had been planned to build eight of these guns to arm Agincourt, Minotaur and Northumberland, but only two were completed and they were used as powder proof guns. These were some of the first Woolwich all-steel guns, and are considered to be one of their worst designs. The hoops were constructed of hammer-welded steel coils. The forged trunnion piece was screwed to the breech coil and originally they were not chase hooped. Actual bore length was 25.5 calibers as built and somewhat shorter after chase hooping.
Generally similar to the Mark I, the only difference being that the bore length was 29.5 calibers. It had been intended to construct eight guns but only two were completed and they were only used as powder proof guns. They were later relined down to 6" (15.2 cm) and then chambered the same as the 6" (15.2 cm) Mark VII.
The construction of these guns was improved over the earlier ones, with the hoops machined from steel forgings. Actual bore length was 25.6 calibers. Construction was 'A' tube/breech piece, 'B' hoop, 'B' tube with 'B' hoop linked to the breech piece by a key hing in halves, five hoops including trunnion hoop over key ring and breech piece, and small hoop over the muzzle. The breech block screwed into the breech piece and there was a bronze sheath over the breech end as hood and counterweight. The elevating band was shrunk on. Later chase hooped to improve strength. HMS Bellerophon mounted ten guns which were not chase hooped at the time. These were on VB Mark I mountings which had an elevation range of -4.5 to +10 degrees. A single chase hooped gun was carried by the gunboats Bustard, on VB Mark I mounting, and by Bonetta, Pike and Snap on VCP Mark I mountings which allowed an elevation of -5 to +15 degrees. Fourteen guns were made by Woolwich and a further 10 guns by Elswick where they were known as EOC Pattern E.
With a 210 lbs. (95 kg) projectile and using a charge of 104 lbs. (47.2 kg) Prismatic Brown, these guns had a muzzle velocity of 1,953 fps (595 mps) and a range of 7,200 yards (6,580 m) at an elevation of 10 degrees. Cord 20 charges were used later and these were 28.7 lbs. (13.0 kg) and gave a muzzle velocity of 1,987 fps (606 mps).
Similar to the Mark III but with a bore of 29.6 calibers. Two guns were made by Woolwich and a further eleven by Elswick where they were known as EOC Pattern F. Later chase hooped similar to the Mark III, but now with 5B and 1C hoops and the trunnions were moved 9.4 inches (24 cm). A total of 13 guns were made, 2 by the Royal gun Factory and 11 by EOC as Pattern F. Two each were used on Mersey, Severn, Foth and Thames on VCP Mark I mountings which had an elevation range of -5 to +15 degrees.
With a 210 lbs. (95 kg) projectile and using a charge of 118 lbs. (53.5 kg) Prismatic Brown, these guns had a muzzle velocity of 2,150 fps (655 mps) and a range of about 10,700 yards (9,780 m) at an elevation of 15 degrees. Cord 20 charges were used later and these were 32.6 lbs. (14.8 kg) and gave a muzzle velocity of 2,145 fps (654 mps).
This gun was never made. It was not chase hooped and differed from the Mark III in having fewer external components and an alpha tube and liner inside the A tube. Actual bore length was to be 25.6 calibers.
This gun was designed as a 29.6 caliber version of the Mark V, but its design was altered to a more complex set of hoops. Construction was A tube/breech piece, taking breech block, 1B tube, 2B tube to muzzle/C tube over part of 1B and 2B/jacket interlocking with breech piece, trunning ring interlocking with C tube and breech piece, D hoop. These guns were used to arm the Indian monitors Magdala and Abyssinia, replacing their original 10" (25.4 cm) RML guns. The gun was designed by the Royal Gun Factory but all nine completed were built by Elswick, who appear not to have assigned a Pattern letter. Performance was similar to the Mark IV. The original twin mountings, which had been used for 10 inch (25.4 cm) RML guns, were converted by Elswick to hydraulic training and the new guns were now in Vavasseur mountings. Elevation is not certain, possibly the same 13 degrees as the original 10 inch (25.4 cm) guns.
A throwback to the designs of the earliest 8" (20.3 cm) guns, with construction being of mixed steel and wrought iron construction. Five of these 26 caliber guns were purchased from Elswick with four of these being mounted at Singapore in obsolete long recoil barbette mountings. Some were chase hooped before completion with a reduction to 25.5 calibers. One of the guns that was not chase hooped blew off its muzzle in 1891. These guns were replaced by the Mark VIIA of 26 calibers which was similar in construction to the Mark VI.
The original Mark VII was EOC Pattern 'H' and guns of this same general type were mounted in vessels of the Australian states and in Australian and New Zealand coastal defences. Pattern 'D' was in Albert and Protector, Pattern 'E' was in Victoria, Pattern 'G' in Gayundah and Paluma. Pattern 'I' was in Australian coast defenses and Pattern 'L' was in New Zealand Coast defenses.
These were the last 8" (20.3 cm) guns in British service until the Washington Treaty cruisers were built in the 1920s.
- "British Naval Guns 1880-1945 No 8" article by John Campbell in "Warship Volume VII"
- "British Battleships: 1860 - 1950" by Oscar Parkes
- 22 July 2006
- 15 February 2009
- Fixed typographical error, added usage information for the Mark IV
- 04 March 2009
- Added details for Mark VII