Diametre:	20 mm
Mass of the system:	480 kg (without ammunition)
Elevation:	-15° to + 90°
Range:	17000 m (elevation 40°)
Maximum practical range:	2000 m against aerial targets Wikipedia does not have an article with this exact name. ...
Speed of the shell:	820 m/s
Rate of fire:	450 round/min

The design of the Oerlikon 20mm cannon, by Reinhold Becker dates back to 1914, and is still in use today, after having been used extensively during the Second World War. Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km into the air. ...

History

The German Army was the first user, mounting it on its aircrafts during the First World War. In 1919, the patent is transefered to Switzerland, and the production is assumed by Semag, later bought by Werkzeug Maschinenfabrik Oerlikon. Most of the main parties of the Second World War would buy licenses to manufacture the cannon themselves.

In 1935, the cannon was adapted by Great Britain to be used as a naval artillery piece, in a short-range anti-aircraft role. It came to be famous in this role, notably against Japanese kamikaze during the Pacific War. A kamikaze, a Mitsubishi Zero in this case, about to hit the USS Missouri. ...

It is still in use today on some naval units, theorically as a last-recourse anti-air weapon, but mainly used for police shots (warning shots or incapaciting shots). A warning shot is a harmless artillery shot intended to call attention. ...

Description

The Oerlikon 20mm cannon is a monotube cannon with a large coil around it. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ...

In its naval version, it is fixed on a mount, and protected by two pieces of armour. The cannon is manned by the gunner (who aims and fires the piece), the piece chief (designating objectives) and the feeder (bringng fresh ammunition).

The gun is namoeuvered by the body of the gunner, who is attached to the weapon. The fire is directed through an optical visor used on the Bofors 40 mm gun as well. 40 mm Bofors Polish-made Bofors gun after the Battle of Bzura The Bofors 40 mm gun is a famous autocannon designed by the Swedish firm of Bofors. ...

The feeding is done through a cylindrical magasine on the top of the gun. A trigger in teh right-hand cross commands the fire. After a shot, discarded cartridges are ejected under the waepon.