View source for 305 mm/45 Mark X (305 mm)

== Description ==
''Write an introduction to the article in 2-3 small paragraphs. Briefly tell us about the history of the development and combat using the weaponry and also about its features. Compile a list of air, ground, or naval vehicles that feature this weapon system in the game.''

=== Vehicles equipped with this weapon ===
<!-- ''List out vehicles that are equipped with the weapon.'' -->

* {{Specs-Link|uk_battlecruiser_invincible}}
* {{Specs-Link|uk_battleship_dreadnought}}

== General info ==
''Tell us about the tactical and technical characteristics of the cannon or machine gun.''

=== Available ammunition ===
<!-- ''Describe the shells that are available for the weapon and their features and purpose. If it concerns autocannons or machine guns, write about different ammo belts and what is inside (which types of shells).'' -->
{| class="wikitable sortable" style="text-align:center" width="100%"
! colspan="8" | Penetration statistics
|-
! rowspan="2" data-sort-type="text" | Ammunition
! rowspan="2" | Type of<br>warhead
! colspan="6" | Penetration @ 0° Angle of Attack (mm)
|-
! 1,000 m !! 2,500 m !! 5,000 m !! 7,500 m !! 10,000 m !! 15,000 m
|-
| Mark IIa HE || HE || 72 || 72 || 72 || 72 || 72 || 72
|-
| Mark VIa APC || APC || 493 || 437 || 359 || 298 || 250 || 190
|-
| Mark VIIa SAPCBC || SAPCBC || 265 || 234 || 192 || 159 || 133 || 101
|-
|}
{| class="wikitable sortable" style="text-align:center" width="100%"
! colspan="10" | Shell details
|-
! rowspan="2" data-sort-type="text" | Ammunition
! rowspan="2" | Type of<br>warhead
! rowspan="2" | Velocity<br>(m/s)
! rowspan="2" | Projectile<br>mass (kg)
! rowspan="2" | Fuse delay<br>(s)
! rowspan="2" | Fuse sensitivity<br>(mm)
! rowspan="2" | Explosive mass<br>(TNT equivalent) (kg)
! colspan="3" | Ricochet
|-
! 0% !! 50% !! 100%
|-
| Mark IIa HE || HE || 831 || 386 || 0 || 0.1 || 53.13 || 79° || 80° || 81°
|-
| Mark VIa APC || APC || 831 || 389.8 || 0.025 || 17 || 13.64 || 48° || 63° || 71°
|-
| Mark VIIa SAPCBC || SAPCBC || 831 || 386 || 0.035 || 17 || 36.3 || 48° || 63° || 71°
|-
|}

=== Comparison with analogues ===
''Give a comparative description of cannons/machine guns that have firepower equal to this weapon.''

== Usage in battles ==
''Describe the cannon/machine gun in the game - its distinctive features, tactics of usage against notable opponents. Please don't write a "guide" - do not impose a single point of view, but give the reader food for thought.''

=== Pros and cons ===
''Summarise and briefly evaluate the weaponry in terms of its characteristics and combat effectiveness. Mark pros and cons as a list.''

'''Pros:'''

*

'''Cons:'''

*

== History ==
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The 12-inch 45-calibre Mark X guns were the tenth series of guns made in the 12-inch calibre by the Royal Navy and were used in a design that changed the face of battleship construction. The calibre was first adopted by the British in the 1880s when the decision was made to adopt breech-loading naval guns and became standard in the 1890s when the British began switching to cordite ammunition. As naval gunnery improved during the turn of the century, particularly thanks to the efforts of the American William Sims and Britain's own Percy Scott, combat was being extended to the unprecedented range of 6,000 yards. Another important innovation was in constructing naval guns as technology allowed for longer and longer barrels, Vickers kept making guns that were as long as they could get away with. Compared to the earlier Mark IX guns, the Mark X had a 540-inch long bore from 480 inches and a muzzle velocity of 2,700 feet per second, 1,000 more than the Mark IX's. The Mark X guns were first built for the ''Lord Nelson''-class of pre-dreadnought battleships, but the design was delayed and instead the first ship launched carrying this weapon was [[HMS Dreadnought|HMS ''Dreadnought'']]. While the premise of a battleship with all-big-gun armament was floated around by Italian naval architect Vittorio Cuniberti in a 1903 article in ''Jane's Fighting Ships'', HMS ''Dreadnought'' was the first ship completed to such specifications, despite the Royal Navy only beginning taking the concept seriously after noticing the 12-inch guns were the most effective during the naval battles of the Russo-Japanese War. The other nations were not far behind in what became a naval arms race that would affect navies all over the world as they drove to make their dreadnoughts. The United States had already approved of a similar design that became the ''South Carolina''-class and Japan had already the ''Satsuma'' as an all-big-gun design, though it wasn't completed as one. Alongside HMS ''Dreadnought'', these guns were also used by the [[HMS Invincible|''Invincible'' class]], a new breed of battlecruisers designed to combine high speed with the firepower of a dreadnought. They were also used on the follow-up design to these ships, the ''Bellerophon''-class dreadnoughts and the ''Indefatigable''-class battlecruisers. However, with the beginnings of a naval arms race, the Mark X did not satisfy the Royal Navy's needs for long and was soon replaced by the [[12 inch/50 Mark XI (305 mm)|12 inch/50 Mark XI]]. However, it would see use during World War I both on British warships and defend the Allied-controlled Belgian coast near Nieuwpoort in 1917.

== Media ==
''Excellent additions to the article would be video guides, screenshots from the game, and photos.''

== See also ==
<!-- ''Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:''
* ''reference to the article about the variant of the cannon/machine gun;''
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* [[12 inch/50 Mark XI (305 mm)]]- Longer barrel variant.

== External links ==
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* ''topic on the official game forum;''
* ''other literature.''

{{Britain naval cannons}}

[[Category:Naval cannons]]