The Oerlikon 20 mm cannon
is a series of autocannons
, based on an original
design by Reinhold Becker
of Germany, very early in World War I
, and widely produced by Oerlikon Contraves
and others. Various models of Oerlikon cannon were used during World War II
, and they are still in use today.
During World War I
, the German Reinhold Becker
developed a 20 mm cannon, known now as the 20 mm Becker
using the Advanced Primer Ignition blowback
(API blowback) method of operation. This used a 20x70 RB cartridge and had a cyclic rate of fire of 300 rpm. It was used on a limited scale as an aircraft gun and an anti-aircraft gun towards the end of that war.
Because the treaty of Versailles banned further production of such weapons in Germany, the patents and design works were transferred in 1919 to the Swiss firm SEMAG (Seebach Maschinenbau Aktien Gesellschaft
) based near Zürich. SEMAG continued development of the weapon, and in 1924 had produced the SEMAG L
, a heavier weapon (43 kg) that fired more powerful 20x100RB ammunition at a slightly higher rate of fire, 350 rpm.
In 1924 SEMAG failed. The Oerlikon firm, named after the Zürich suburb where it was based, then acquired all rights to the weapon, plus the manufacturing equipment and the employees of SEMAG.
In 1927 the Oerlikon S
was added to the existing product line. This fired a still larger cartridge (20x110RB) to achieve a muzzle velocity of 830 m/s (versus 490 m/s for the original Becker 20x70RB... Read More