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RBL 20 pounder gun
RBL 20 pounder Armstrong field gun.jpg
16 cwt field gun with limber
Type Naval gun
Field gun
Place of origin  United Kingdom
Service history
In service 1859 - 19??
Used by British Empire
Production history
Designer W.G. Armstrong Co.
Number built 412[1]
Specifications
Weight Naval : 13 long hundredweight (660 kg) or 15 long hundredweight (760 kg)
Field : 16 long hundredweight (810 kg)[2]
Barrel length Naval : 54 inches (1.372 m)
Field : 84 inches (2.134 m) bore & chamber[2]

Shell 21 pounds 13 ounces (9.894 kg)[2]
Calibre 3.75-inch (95.2 mm)
Breech Armstrong screw with vertical sliding vent-piece (block)
Muzzle velocity Naval : 1,000 feet per second (300 m/s)
Field : 1,130 feet per second (340 m/s)[3]
Effective range 3,400 yards (3,100 m)

The Armstrong Breech Loading 20 pounder gun, later known as RBL 20 pounder, was an early modern 3.75 inch rifled breech-loading light gun of 1859.

History[edit | edit source]

The gun was effectively a larger version of the successful RBL 12 pounder 8 cwt Armstrong gun. There were different versions for Land and Sea service.[4]

Sea service[edit | edit source]

13 cwt boat gun at Hong Kong Museum of Coastal Defence

The RBL 20 pounder of 13 cwt and 15 cwt for sea service was introduced in 1859. It is 2½ feet shorter than the land version giving it a bore of only 54 inches (14.43 calibres), and hence a short stubby appearance. Its short barrel only allowed it to attain a muzzle velocity of 1,000 ft/second.

The 15 cwt gun, identifiable by the raised coil in front of the vent slot, was intended for broadside use in sloops. The more lightly constructed 13 cwt gun was known as a pinnace gun and was intended for boat use.[5]

Land service[edit | edit source]

The RBL 20 pounder of 16 cwt for land service was introduced in 1860. It has a bore of 84 inches (22.36 calibres) and hence has the appearance of a typical field gun.

Surviving examples[edit | edit source]

See also[edit | edit source]

Notes and references[edit | edit source]

  1. 412 were in service in 1877 : 89 16cwt (land service), 31 15cwt & 292 13cwt (sea service). Quoted in Treatise on Manufacture of Ordnance 1877, page 150. Holley 1865, page 13 quotes 257 as at 1863 : 9 land service & 1 sea service manufactured by Elswick Ordnance, 16 land service and 231 sea service by the Royal Gun Factory. From the Report of the Select Committee on Ordnance, 1863.
  2. 2.0 2.1 2.2 Text Book of Gunnery, 1887
  3. 1130 ft/second firing a 21 lb 13 oz projectile, using 2 lb 8 oz R.L.G.2 (gunpowder) propellant. Text Book of Gunnery, 1887
  4. Treatise on Manufacture of Service Ordnance, 1877
  5. Owen 1873, page 53

Bibliography[edit | edit source]

External links[edit | edit source]


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