1.1 inch/75 Mk.1 (28 mm)

The 1.1 inch/75 Mk.1 (28 mm) on USS Atlanta

Description

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.

General info

Tell us about the tactical and technical characteristics of the cannon or machine gun.

Available ammunition

Penetration statistics
Ammunition	Type of warhead	Penetration @ 0° Angle of Attack (mm)
		10 m	100 m	500 m	1,000 m	1,500 m	2,000 m
Mk.1 HE-T	HEF-T*	2	2	2	2	2	2

Shell details
Ammunition	Type of warhead	Velocity (m/s)	Projectile mass (kg)	Fuse delay (m)	Fuse sensitivity (mm)	Explosive mass (TNT equivalent) (g)	Ricochet
							0%	50%	100%
Mk.1 HE-T	HEF-T*	823	0.42	0	0.1	14.7	79°	80°	81°

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

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 If the historical reference turns out to be too long, take it to a separate article, taking a link to the article about the weapon and adding a block "/History" (example: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

Media

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

See also

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• 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.