Restored 3"/50 caliber gun Mark 22 mounted on deck of former Cannon-class destroyer escort museum ship USS Slater DE-766.


The 3″/50 (7.62 cm) caliber gun Mark 22 was a US naval gun of a simpler construction than the previous class of 3" guns, and successive versions were improved designs. This gun was widely used up to the 1930s, but were then gradually replaced on larger ships by 5"/25 (12.7 cm) single mountings and later by Bofors 40mm guns in twin and quad mountings. During World War II, this weapon was extensively used on smaller warships such as destroyer escorts, submarines and auxiliaries along with many merchant ships, with about 14,000 guns being produced between 1940 and 1945.

Although considered to be dual-purpose weapons, these guns initially had limited effectiveness in either surface or anti-air roles, as they were manually operated, meaning that they could not be fitted for remote power control (RPC), and they fired lightweight shells. However, the invention of the variable time (VT) proximity fuse and the addition late in the war of power operation together with the Mark 51 director system greatly improved their effectiveness as AAA guns, giving the later marks of this weapon a new lease on life. In the end of 1945, a 3"/50 with director control, RPC and VT ammunition was considered superior to a twin Bofors 40mm mount and at least equivalent to a quad Bofors 40mm mount.

Powers and Stats

Tier: 9-B

Name: 3”/50 caliber Mark 22

Origin: Real World

Age: 1944–present

Classification: Frigate & Destroyer Escort Main Gun, Anti-Aircraft Gun

Attack Potency: Wall level (2.57–3.4 megajoules); 15–20 rounds per minute rate of fire

Speed: Supersonic (820–825 meters per second)

Durability: At least Wall level, at most Small Building level with biggest turret mount in terms of total destruction (comprised of up to 5098 kilograms of steel with a fragmentation energy of 135 megajoules)

Stamina: Barrel life of 4300 rounds

Range: Up to over 13.4 kilometers (AA ceiling of over 9 kilometers)

Weaknesses: Manually loaded, requires about 5–7 men to operate one turret; when the breech block was closed, the firing pin could stick out and strike the cartridge igniter and accidentally fire the gun.

Note: Similar naval guns of about the same bore (70-80mm) and period generally have performance equivalent to this one.

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