The Oerlikon 20 mm cannon is a series of autocannons based on an original German Becker Type M2 20 mm cannon design that appeared very early in World War I. It was widely produced by Oerlikon Contraves and others, with various models employed by both Allied and Axis forces during World War II .

This is a list of naval guns of all countries ordered by caliber.

The Nexter Narwhal is a type of remotely operated naval artillery turret made by the French company Nexter. It houses a 20 mm autocannon based on the Nexter M621 and M693. The name "Narwhal" is a backronym of "NAval Remote Weapon, Highly Accurate, Lightweight". [2]

Mar 18, 2019 · Adopted by the U.S. Navy in November 1940, the Oerlikon 20 mm was operated by a crew of four: the gunner, loader, spotter, and gun captain. It provided effective short-range defense against aircraft that the .50-caliber Browning or the quad 1.1-inch could not.

20 mm Oerlikon guns on USS Iowa BB-61 about 1943. The crewman on the left of the elevated gunmount is adjusting the trunnion height. Note the Mark 14 Gunsight and that the censor has obscured the radar antennas on the director and mast. U.S. Naval Historical Center Photograph # …

20 mm Mark 16 Mod 5 mounted on a Mark 67 Mod 1 gun mount in March 1971. U.S. Navy Photograph No. DN-SC-90-01951.

One of the most widely used naval weapons of World War II, the 20-mm Oerlikon antiaircraft cannon was installed aboard virtually every U.S. Navy warship—from lowly PT boats to massive battleships—as well as in auxiliaries and armed merchantmen.

The Oerlikon gun was fielded in United States Navy ships starting in 1942, replacing the M2 Browning machine gun, which lacked range and firepower. It became famous in the naval anti-aircraft role, providing an effective defense at short ranges (in practice up to 1.5 km) at which heavier guns had difficulty tracking a target.

The 20mm Oerlikon gun is one of the most rug­ged machine guns ever built. It has only a few moving parts and if these parts and the barrel are given a small amount of care the gun will al­ways be ready to fire, and few difficulties will de­velop.

Apr 17, 2013 · The US Navy rapidly discarded and scrapped their 20mm guns in service throughout the Cold War, just keeping a few around after 1955 for use against small boats.