BL 9 . 2 inch gun Mk IX – X The BL 9 . 2 inch guns Mk IX and Mk X were British 46 . 7 calibres naval and coast defence guns in service from 1899 to the 1950s . They had possibly the longest , most varied and successful service history of any British heavy ordnance . History . These guns succeeded the 9 . 2 inch Mk VIII and increased the bore length from 40 to 46 . 7 calibres , increasing the muzzle velocity from to . Mk IX was designed as a coast defence gun , with a three - motion breech . Only fourteen were built and the Mk X , introduced in 1900 , incorporated a single - motion breech and changed rifling , succeeded them . As coastal artillery , the Mk X remained in service in Britain until 1956 , and in Portugal until 1998 . Two - hundred and eighty - two of the Mark X version were built by Vickers , of which twenty - eight examples are known to survive today , all except one fitted on barbette mounts . One in Cape Town is on a disappearing mount . The 9 . 2 inch Mk XI gun introduced in 1908 increased the bore length to 50 calibres in an attempt to increase the velocity still further , but proved unsuccessful in service and was phased out by 1920 . Mk X was hence the final Mark of 9 . 2 inch guns in British Commonwealth service . Design . These were medium - velocity wire - wound guns with Welin interrupted screw breeches . Naval service . Royal Navy . Mark X guns were mounted on : Greek Navy . 4 guns of 45 calibres ( 414 inches ) bore produced by Elswick Ordnance Company were mounted in 2 twin turrets on the Greek cruiser " Georgios Averof " in 1910 , instead of the 10 - inch guns mounted on her sisters of the " Pisa " - class in Italian service . These were similar to the 4 Vickers 45 - calibre export model guns used by Britain as railway artillery on the Western Front in World War I under the designation BL 9 . 2 inch gun Mark XIV . They fired the same 380 - pound shell using the same 120 - pound cordite charge as the British service Mk X gun , and it may be assumed that its performance was very similar . British coastal deployments . These guns were ' counter - bombardment ' guns designed to defeat ships up to heavy cruisers armed with 8 - inch guns . They were deployed in the fixed defences of major defended ports throughout the British Empire until the 1950s . Their role was to defeat enemy ships attacking the ships in a port , including warships , alongside or at anchor in the port . However , where guns covered narrows , such as the Dover Straits , the Straits of Gibraltar , or " the Narrows " of Bermuda , they also had a wider role of engaging enemy ships passing through the straits . Normally deployed in batteries of two or three guns , a few major port had several batteries positioned miles apart . There were several marks of mountings and a battery had extensive underground facilities in addition to the guns visible in their individual gun - pits . Together with the 6 - inch Mk VII , they provided the main heavy gun defence of the United Kingdom in World War I . 3 Mk IX and 53 Mk X guns were in place as at April 1918 . Mounting . The Mounting Barbette Mark V ( the original mounting with Mark IX and X guns ) gave a maximum elevation of 15 degrees , and maximum range of 21 , 000 yards . This and some modified to Mark VI ( 30 degrees and 29 , 500 yards ) were manually powered , the projectile and propelling charge were manually hoisted to loading level , the projectile manually loaded and rammed , and traverse and elevation were by handwheels . There was an elevated platform around the breach area for the gun detachment commander ( No 1 ) and some detachment members , and a gun shield to the front . The ordnance and mounting together weighed some 125 tons , they were well balanced and the handwheels needed very little effort to move the gun . However , the Mark VII mounting appeared in the 1930s and in 1939 a simplified version , Mark IX . Both were hydraulically powered and the platform was enclosed in a roofed gun house with three sides ( and rear with Mark IX ) . The hydraulics meant that both projectile and propelling charge could be hoisted in a single load . With Mark VII and IX the maximum elevation was increased to 35 degrees to give a maximum range of 36 , 700 yards . Installation . Each gun mounting was installed on a central cast - steel pedestal in an open concrete gunpit 35 feet in diameter and 11 feet deep . The gun and mounting weighed 125 tons . A very narrow gauge rail track was embedded around the gunpit floor . A trolley was manhandled around the track between the two ammunition lifts ( one for projectiles , one for propelling charges ) and the rear of the gun ( this position varied depending on where the gun was pointed ) . Below the gun pit were the separate ammunition bunkers for projectiles and shells with direct access to the ammunition lifts . These bunkers had an access road leading to them for ammunition re - supply . The guns presented only a very small target above ground level , guns and gunpits were camouflaged . Organisation . Two or three guns comprised a named battery position with the guns manned by a Heavy Battery . For example in 1940 Madalena and Bijemma Batteries , both with 9 . 2 in Malta were manned by 6 Heavy Battery RA of 4 Heavy Regiment RA . Increasing range led to new centralised control arrangements . Fortress observation posts , equipped with rangefinders and directors were sited 4000 – 10 , 000 yards apart to give observation of all the sea area within range . They reported enemy ship bearings and distances to the ‘ Fortress Plotting Centre ’ ( FPC ) where the attackers ' positions and courses were plotted , converted to coordinates and then assigned as targets to batteries by the fire commander . The details were telephoned to batteries . The battery plotting room used a Coordinate Converter to turn the coordinates into bearings and elevations and transmitted them to the guns where pointers were matched by changing the guns ’ traverse and elevations . The Observers also reported fall of shot relative to the targets , the FPC used an Encoder to convert these into a Clock Code , which the battery converted to its Left / Right , Add / Drop corrections . Various types of radars integrated into the fire command soon became widespread in WW2 and enabled effective night engagements . Deployments . The following table summarises the deployment of 9 . 2 inch guns . It is possible that some 1914 guns were still the older Marks . * indicates deployment was not completed until after 1940 . A third Canadian battery was not completed until after World War II . The three guns in Bermuda remained in battery through the Second World War ( and are still in situ ) , but were not actively utilised . Portugal has several surviving examples , with live firings as recently as December 10 , 1998 . The Portuguese refer to these guns as 23 . 4 cm guns , made by Vickers . Deployment on railway trucks . In 1916 Elswick adapted a small number of Mk X guns , 2 Mk X variants originally intended for coast defence in Australia , and 4 45 - calibre Vickers export guns ( under the designation 9 . 2 inch gun Mk XIV ) and mounted them on Mk 3 railway truck mountings for service on the Western Front in France and Belgium . Belgian coast . From 1917 several Mk X guns were deployed ashore on the section of the Belgian coast still held by the Allies , near Nieuport . They were part of the " Royal Naval Siege Guns " under the command of Admiral Sir Reginald Bacon , and were used for attacking German heavy gun batteries . Other deployments . In the 1950s , Canadian guns were transferred under NATO auspices , to Portugal ( Azores ) and Turkey . It is unclear if any UK guns were also transferred . Surviving examples . Click on the coordinate links in the following list to view map location and / or satellite image . There are ten guns in the surrounds of Cape Town , South Africa : Near Simonstown three 9 . 2 inch guns in the Scala Battery : Above Llandudno three 9 . 2 inch guns in the Apostle Battery : On Robben Island three 9 . 2 inch guns in the De Waal Battery : Near central Cape Town one 9 . 2 inch gun in a unique “ disappearing mount ” in Fort Wynyard : On the Durban Bluff , South Africa , three 9 . 2 inch guns in the Da Gama Battery : On Rottnest Island , off Fremantle , Western Australia two 9 . 2 inch guns in the Oliver Hill Battery : In Portugal ' s Bateria da Raposa , near Fonte da Telha , three 9 . 2 inch guns in good condition : In Portugal one 9 . 2 inch gun of the original three of the Alcabideche battery , near Cascais is preserved in place in the grounds of the new Cascais Hospital : On the Rock of Gibraltar , three 9 . 2 inch guns : In Burmuda , two guns survive on St . David ' s Island , on Mark V Barbette mounts , at St . David ' s Battery , overlooking the Narrows Channel that leads to St . George ' s Harbour , in Bermuda , as well as to the Royal Naval Dockyard , Bermuda , the Great Sound , Hamilton Harbour , and Murray ' s Anchorage . The battery forms part of Great Head Park , and there is public access . A third at Fort Victoria , on St . George ' s Island , is being relocated to the Bermuda Maritime Museum at the Royal Naval Dockyard , Bermuda to make way for a hotel development . : The official opening of the restored De Waal Battery on Robben Island , near Cape Town , South Africa , took place on the 4th of March , 2011 . The ceremony involved the unveiling and demonstration of the No 3 Gun of the battery of three " Ordnance BL 9 . 2in Coast Defence Guns " . The gun in question , an " Ordnance BL 9 . 2in Coast Defence Gun on a Mk VII mounting " , has been restored as a moving display , with all the hydraulics working , enabling the turret to be fully traversed through 360° , the gun being elevated to 25° and the loading / ramming mechanism fully operational . Of the original ninety - eight 9 . 2 inch guns that did service worldwide during WWII , only about twenty - eight remain . Of these twenty - eight , twelve are in South Africa , the De Waal Battery No . 3 gun being the only gun in the world that has been restored as a moving display . Plans are afoot to restore the nearby Scala Battery at Simon ' s Town as a static display . On Western Australia ' s Rottnest Island the H1 gun and associated underground resources is open to visitors as a static display . On 10 December 1998 the Portuguese Coast Artillery , fired the last shots from the 6th Battery of their " Fonte da Telha " 9 . 2 inch ( 23 . 4 cm ) guns . The fate of the several Coast Artillery Regiment batteries and their weapons has not yet been determined , but it is known that it is the intent of the Army to conserve one future Museum of Coast Artillery . British ammunition up to World War I . Shells up to and including World War I were not streamlined , typically having fairly blunt noses of 2 C . R . H . . British World War II ammunition . World War II ammunition was somewhat streamlined , typically with ballistic caps of 4 or 5 / 10 C . R . H . , but still retained square bases rather than the tapered type base typical of projectiles for more modern guns in use in World War II . " Super " charges of 124 pounds cordite SC 205 were available , which boosted the muzzle velocity to