Ordnance QF 20-pounder

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The Ordnance QF 20 pounder (known as 20 pounder, 20 pdr or simply 20-pr) was a British 84 mm (3.307 inch) tank gun.[1][i] It was introduced in 1948 and used in the Centurion main battle tank, Charioteer medium tank, and Caernarvon Mark II heavy tank. The 20 pounder was designed to replace the Ordnance QF 17 pounder, which had proven itself effective in World War II. However, once the 20 pounder gun was found to have inadequate performance against the Soviet T-54, the gun was mostly replaced in service by the larger calibre 105 mm L7 gun.

Ordnance QF 20 pounder Mark I
Charioteer-latrun-2.jpg
Charioteer tank equipped with the 20 pounder. This gun is a later model which is fitted with a bore evacuator
Typetank gun
Place of originUnited Kingdom
Service history
In service1948–1970s
Used byUnited Kingdom
Australia
Austria
Canada
Finland
Israel
Jordan
Lebanon
South Africa
WarsKorean War
Vietnam War
Six-Day War
South African Border War
Specifications
Length226.4 in (5.75 m), 66.7 calibres

Shell84×618mm R
Calibre84 millimetres (3.31 in)
Elevation+18 to −10 in Centurion Mk 5

Design and developmentEdit

The gun was developed by the Royal Ordnance Factories.

As fitted to the Charioteer, it ran through two models:

  • Model A without a fume extractor.
  • Model B with a fume extractor.

The L7 105 mm tank gun was developed from the 20 pounder. In 1954, the original version of the 105 mm was made by re-boring the tube of a 20 pounder barrel.[2]

Service historyEdit

The gun was fitted predominantly to the Centurion tank, seeing action with British and Australian forces during the Korean and Vietnam War. When a Soviet T-54A main battle tank was driven to the British embassy in Budapest by Hungarian rebels during the Hungarian Revolution of 1956, analysis of its armour and 100 mm gun led British officials to determine that the 20 pounder was ineffective at defeating Soviet armour. This led to the development of the 105 mm L7 tank gun, which was designed to fit specifically into the turret mountings of the 20 pounder, facilitating for easily upgunning existing tanks equipped with the 20 pounder. [3]

One 20 pounder gun was fitted to a Swiss pre-production Panzer 58, replacing a domestic 90 mm Kanone 1948 gun, before it was equipped with the 105 mm L7.[4]

PerformanceEdit

The 20 pounder's APCBC projectile had an initial muzzle velocity of 1,020 metres per second and could penetrate 210 mm (8.3 in) of rolled homogeneous armour (RHA). However, these conventional rounds were rarely used.

The APDS projectile had a muzzle velocity of 1,465 m/s (4,810 ft/s) and the APDS Mk.3 shell could penetrate 330 mm (13 in) of RHA at a distance of 1000 yard.[5][6][ii][7]

The 20-pounder could also fire high-explosive and canister shot shells.

AmmunitionEdit

 
20 pdr HE round
Round Muzzle velocity[8]
APDS 4,700 ft/s
HE 1,975 ft/s
Canister 3,000 ft/s
Smoke 825 ft/s

FootnotesEdit

NotesEdit

  1. ^ The gun is specified as 83.4 mm (3.283 in) here, while Ogorkiewiecz states the weapon was 83.8 mm. Norman gives it as "3.3 inch (84 mm)"
  2. ^ The 20 pounder's APDS round had twice the penetration capability of an 8.8 cm AP round.

ReferencesEdit

  1. ^ Pugh (1962), p. 34.
  2. ^ Ogorkiewicz (1991), p. 70.
  3. ^ Zaloga, Steve, 1952- (2004). T-54 and T-55 main battle tanks 1944-2004. Johnson, Hugh, 1971-. Oxford: Osprey. ISBN 1841767921. OCLC 60834392.CS1 maint: multiple names: authors list (link)
  4. ^ Ford (1997), p. 121.
  5. ^ "British Anti-Tank Gunnery Data". figuras.miniatures.de.[unreliable source?]
  6. ^ Dunstan (2003), p. 10.
  7. ^ Archive:Tank effectiveness: Conqueror, Conway and Charioteer & WO 291/1416 (1954), p. 9.
  8. ^ Norman (1967), p. 12.

BibliographyEdit

See alsoEdit

External linksEdit