Polsten

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Polsten
Type	Autocannon
Place of origin	Poland
Service history
In service	1944 - 1950s
Used by	United Kingdom
Specifications
Weight	126 lbs (57 kg)
Length	84 in
Barrel length	57 in (barrel)

Calibre	20 mm
Rate of fire	450 rpm
Muzzle velocity	2725 fps (830 mps)
Maximum range	2000m (effective 1000m)
Feed system	60 round drum magazine or 30 round box magazine

The Polsten was a low cost Polish made 20 mm autocannon developed from the Oerlikon gun. The Polsten was designed to be simple and much cheaper to build than the Oerlikon without reducing effectiveness. When Nazi Germany invaded Poland in 1939, the design team escaped to England and resumed work. The need for the Polsten was apparently mooted in June 1941. It went into service in March 1944 alongside the Oerlikon. Both the Oerlikon and the Polsten used similar 60 round drum magazines, however, the Polsten could use a simpler box magazine with 30 rounds. It remained in service into the 1950s.

The Polsten was used as a substitute for the Oerlikon in the same roles, one of which was as an airborne unit anti-aircraft gun. It was used on a wheeled mounting that could be towed behind a jeep.

Various double, triple and quadruple mounts were developed. John Inglis Limited of Toronto, Ontario, Canada produced many thousands of guns and some 500 quadruple mountings that saw limited service at the end of the war. These multiple mounts were both trailered and truck mounted.

The Polsten gun was used for armoured vehicles equipped with anti-aircraft guns based on the Cromwell/Centaur tank.

The Polsten was also mounted on early models of the Centurion tank not coaxially with the main gun but in the left hand side of the turret.

The origin of the name is not entirely clear. Some sources suggest Poland and the "Sten Company" to give Pol-sten, though the Sten gun was not made by a Sten Company. Official (United Kingdom) sources indicate the name to have been a compound based on Poland and the Royal Small Arms Factory Enfield in the same manner as the Bren gun (Brno + Enfield) or Sten (Shephard, Turpin + England); also to reflect the gun design being mostly Polish (and the magazine mostly Czech) and the 8 Polish engineers in the design department. The "Sten" ending may also have linked in with the idea of the gun as a cheaper and quicker to produce weapon just like that gun was.