View source for 1.1 inch/75 Mk.1 (28 mm)

[[File:1.1 inch 75 Mk.1.jpg|thumb|x250px|The '''{{PAGENAME}}''' on [[USS Atlanta]]]]
== 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.''-->

The '''1.1 inch/75 Mk.1''', nicknamed the "'''Chicago Piano'''", is an American anti-aircraft gun mounted on early destroyers and cruisers. Meant to replace the M2 Browning, it proved unpopular with its crews due to its unreliability. It was replaced by the 20 mm Oerlikon and 40 mm Bofors wherever possible, with the former having similar performance but requiring far less space, and the latter using the same amount of space but dramatically more effective.

=== Vehicles equipped with this weapon ===
<!-- ''List out vehicles that are equipped with the weapon.'' -->
{{Navigation-Start|Vehicles equipped with this weapon}}

{{Navigation-First-Line|'''Destroyers'''}}{{Specs-Link|us_destroyer_porter_1941}}{{-}}{{Specs-Link|us_destroyer_porter_1942}}{{-}}{{Specs-Link|us_destroyer_somers}}

{{Navigation-Line|'''Light cruisers'''}}{{Specs-Link|us_cruiser_atlanta_class_atlanta}}{{-}}{{Specs-Link|us_cruiser_omaha_class_detroit}}{{-}}{{Specs-Link|us_cruiser_omaha_class_trenton}}

{{Navigation-Line|'''Heavy cruisers'''}}{{Specs-Link|us_cruiser_northampton_class}}{{-}}{{Specs-Link|us_cruiser_pensacola_class}}{{-}}{{Specs-Link|us_cruiser_portland_class}}

{{Navigation-Line|'''Battleships'''}}{{Specs-Link|us_battleship_arkansas}}

{{Navigation-End}}

== 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).'' -->

{{:{{PAGENAME}}/Ammunition|1.1 inch Mk.1 HE-T}}

=== 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:'''

* 4 barrels give a large volume of fire

'''Cons:'''

* Overheats somewhat quickly
* Long reload of 15s
* Only 1 choice of ammo belt
* Low rate of fire, less than the 40 mm Bofors

== History ==
''Examine the history of the creation and combat usage of the weapon in more detail than in the introduction. If the historical reference turns out to be too long, take it to a separate article, taking a link to the article about the weapon and adding a block "/History" (example: <nowiki>https://wiki.warthunder.com/(Weapon-name)/History</nowiki>) and add a link to it here using the <code>main</code> template. Be sure to reference text and sources by using <code><nowiki><ref></ref></nowiki></code>, as well as adding them at the end of the article with <code><nowiki><references /></nowiki></code>.''

== 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;''
* ''references to approximate analogues by other nations and research trees.''

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

{{USA naval cannons}}

[[Category:Naval cannons]]