View source for BL 12 inch Mk X naval gun

{{Infobox Weapon
|is_artillery=yes
|is_explosive= yes
|is_UK=yes
|is_ranged=yes
|image=[[Image:HMSDreadnought gunsLOCBain17494.jpg|300px]]
|caption=On [[HMS Dreadnought (1906)|HMS ''Dreadnought'']]
|name= BL 12 inch gun Mk X
|origin= {{UK}}
|used_by=
|wars=[[World War I]]
|prod_date=
|type=Naval gun
|date= 
|designer=[[Vickers]]
|design_date=
|manufacturer=[[Vickers]]
|service=1906 - 1920s
|caliber= {{convert|12|in|mm|sigfig=4}}
|part_length={{convert|540|in|m|sigfig=4}} bore (45 [[Caliber#Caliber_as_measurement_of_length|cal]])
|carriage=
|breech= 
|rate=
|velocity={{convert|2700|ft/s|m/s|sigfig=3}}<ref>2700 ft/second : As quoted in [http://dreadnoughtproject.org/docs/notes/Range_Tables_for_HM_Fleet_1910.php "Range Tables for His Majesty's Fleet, 1910. February, 1911"]; with 260 lb cordite MD size 45 propellant : [[Treatise on Ammunition]], 1915</ref>
|cartridge={{convert|850|lb|sigfig=4}} [[British ordnance terms#Common Lyddite|Lyddite]], Armour-piercing, [[Shrapnel shell|Shrapnel]]<ref>850 lb shells : [[Treatise on Ammunition]], 1915</ref>
|ammo_wt=
|max_range={{convert|22860|m|yd}}<ref>22,860 metres quoted at : http://navalhistory.flixco.info/H/76624x53535/8330/a0.htm This is understood to be the maximum possible range at 45° elevation, which was possible for siege mountings on land but not for naval mounts</ref>
|recoil=
|weight=57 tons barrel & breech<ref>http://navalhistory.flixco.info/H/76624x53535/8330/a0.htm</ref>
|length= 
|crew=
|number=
<!-- Explosive specifications --> 
|filling_weight=
}}
The '''BL 12 inch Gun Mark X''' was a [[United Kingdom|British]] [[Caliber#Caliber_as_measurement_of_length|45-calibres]] [[naval artillery|naval gun]] which was mounted as primary armament on [[battleship]]s and [[battlecruiser]]s from 1906. It first appeared on the revolutionary {{HMS|Dreadnought|1906|6}}.

==History==
[[Image:HMS Agamemnon (1906) 12-inch gun replacement at Malta 1915.jpg|thumb|left|<center>[[HMS Agamemnon (1906)|HMS ''Agamemnon'']] has her guns replaced during a refit at Malta in May-June 1915</center>]]
[[Image:Ramming12inchShellHMASAustralia1918.jpg|thumb|left|<center>Ramming shell on [[HMAS Australia (1911)|HMAS ''Australia'']], December 1918</center>]]
Mk X continued the trend of lengthening gun barrels as far as new construction methods would permit, in order to allow more cordite propellant to be used to attain higher projectile velocities. Mk X increased the bore length from [[BL 12 inch Mk IX naval gun|Mk IX]]'s 480 inches (40 calibres) to 540 inches (45 calibres), increasing muzzle velocity from 2600 to 2700 feet/second. 

Subsequent British attempts to further increase the power of 12-inch guns led to failure with the 50-calibre [[BL 12 inch Mk XI - XII naval gun|Mk XI and Mk XII guns]]; the Mk X was the last successful 12-inch British gun.

===Naval use===
Mk X Guns were mounted in the following ships which served throughout [[World War I]] :
* {{HMS|Dreadnought|1906|6}} of 1906
* The last 3 ''King Edward VII''-class battleships {{HMS|Africa|1905|6}}, {{HMS|Britannia|1904|6}} and {{HMS|Hibernia|1905|6}}, completed in 1906
* {{Sclass|Lord Nelson|battleship|2}}s laid down 1905, completed 1908
* {{Sclass|Invincible|battlecruiser|2}}s laid down 1906, completed 1908 - 1909
* {{Sclass|Bellerophon|battleship|2}}s laid down 1906, completed 1909
* {{Sclass|Indefatigable|battlecruiser|2}}s laid down 1909, completed 1911 - 1913

===World War I use ashore===
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 [[Reginald Bacon|Admiral Sir Reginald Bacon]], and were used for attacking German heavy gun batteries.

==Ammunition==
{| class="wikitable"
|[[Image:BL12inchCorditeCartridge65lbMkIDiagram.jpg|center|150px]]
|[[Image:12inchCPCMkVIIAShellDiagram.jpg|center|150px]]
|[[Image:HMAS Australia 12 inch shells Closeup.JPG|center|400px]]
|-
|<center>65 lb [[Cordite]] Cartridge ¼ charge</center>
|<center>Mk VIIA [[British ordnance terms#Common Pointed|Common Pointed]] shell with Cap (CPC) filled with gunpowder, 1912</center>
|World War I Shells. Left to Right :
<ul>
<li>Mk XA Capped Armour-Piercing shell filled with Trotyl (TNT)
<li>Shrapnel
<li>Mk 6A Capped Common pointed shell filled with Shellite 70/30
|}

==Surviving examples==
{{Expand section|date=December 2008}}

== See also ==
{{Commonscat-inline}}
*[[305mm/45 Modèle 1906 gun]] French equivalent
*[[EOC 12 inch /45 naval gun]] [[Armstrong Whitworth#Elswick Ordnance Company|Elswick Ordnance Company]] equivalent
*[[12"/45 caliber Mark 5 gun]] US equivalent
*[[List of naval guns]]

==Notes==
{{reflist}}

==References==
==External links==
* Tony DiGiulian, [http://www.navweaps.com/Weapons/WNBR_12-45_mk10.htm British 12"/45 (30.5&nbsp;cm) Mark X]
<br>
{{GreatWarBritishNavalWeapons}}
{{GreatWarBritishWeapons}}

[[Category:Naval guns of the United Kingdom]]
[[Category:305 mm artillery]]
[[Category:Vickers]]

[[ru:12" морское орудие Mark X]]