RBL 20-pounder Armstrong gun

Naval gun

RBL 20-pounder gun
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.
No. built	412^[1]
Variants	13, 15 and 16 cwt^{[note 1]}
Specifications
Mass	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 firing 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

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

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

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. After it became obsolete for regular Royal Artillery use, a small number were re-issued to Volunteer Artillery Batteries of Position from 1889, alongside 16-pounder RML guns and 40 Pounder RBL guns.^[6] The 1893 the War Office Mobilisation Scheme shows the allocation of twelve Artillery Volunteer position batteries equipped with 20 Pounder guns which would be concentrated in Epping, Essex in the event of mobilisation.^[7]

Surviving examples

An unrestored 13 cwt pinnace gun at Hong Kong Museum of Coastal Defence
A 16 cwt gun on board HMS Warrior at Portsmouth, UK
A 13 cwt gun dated 1859 at the Artillery Museum, North Head, Sydney, Australia
Sea Service Pattern at Explosion! Museum of Naval Firepower, Gosport

Notes

^ cwt = long hundredweight = 112 pounds = 51 kg. Hence the 3 models weighed 1456 pounds (660 kg), 1680 pounds (762 kg) and 1792 pounds (813 kg)

References

^ 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.
^ ^a ^b ^c Text Book of Gunnery, 1887
^ 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
^ Treatise on Manufacture of Service Ordnance, 1877
^ Owen 1873, page 53
^ Report on the Account of Army Expenditure from 1888–1889, The National archives, WO33/50
^ Mobilization Tables for Home Defence, List of Militia, Yeomanry and Volunteer Units, HMSO, London, 1893

Bibliography

Treatise on the construction and manufacture of ordnance in the British service. War Office, UK, 1877
Text Book of Gunnery, 1887. London : Printed for his Majesty's Stationery Office, by Harrison and Sons, St. Martin's Lane Archived 4 December 2012 at archive.today
Alexander Lyman Holley, A treatise on Ordnance and Armor published by D Van Nostrand, New York, 1865
Lieutenant-Colonel C H Owen R.A., The principles and practice of modern artillery, published by John Murray, London, 1873

External links

Wikimedia Commons has media related to RBL 20 pounder Armstrong gun.

Handbook for the 20-pr. R.B.L. gun of 16-cwt. on garrison sliding carriage and on travelling carriage, 1892, 1896

British Empire small arms & ordnance of the Victorian era

Sidearms

Muskets and rifles

Artillery

Field Artillery	SBML 9 pounder 13 cwt RBL 9 pounder RBL 12-pounder RBL 20-pounder RML 9-pounder 8 cwt RML 13-pounder 8 cwt RML 16-pounder 12 cwt BL 12-pounder 7 cwt BL 12-pounder 6 cwt QF 12-pounder 8 cwt BL 15-pounder QF 1-pounder pom-pom
Mountain artillery	RML 7-pounder Mountain Gun RML 2.5-inch Mountain Gun
Howitzers, medium, and heavy artillery	RML 6.3-inch howitzer RML 6.6-inch howitzer BL 5-inch howitzer BL 5.4-inch howitzer
Siege & garrison artillery	4.1-inch 'Long Cecil' SBBL 32-pounder SBML 24-pounder SBML 8-inch 65 cwt RBL 40-pounder RBL 7-inch RML 25-pounder 18 cwt RML 40-pounder gun RML 64-pounder 64 cwt gun RML 64-pounder 58 cwt RML 64-pounder 71 cwt gun RML 80-pounder RML 6.6-inch gun RML 8-inch howitzer BL 5-inch gun Mk I – V BL 6-inch 30 cwt howitzer BL 9.45-inch howitzer
Coastal artillery	QF 3-pounder Nordenfelt QF 4.7-inch BL 6-inch Mk III, IV, VI BL 6-inch Mk V RBL 7-inch RML 7-inch RML 8-inch BL 8-inch Mk VII RML 9-inch BL 9.2-inch Mk IV & VI BL 10-inch Mk I BL 12-inch Mk I, VI, VII RML 12.5-inch RML 16-inch RML 17.72-inch

Mortars

13-inch 36 cwt mortar
10-inch 18 cwt mortar
8-inch 9 cwt mortar

War rockets

Congreve 6-pounder
Congreve 12-pounder
Congreve 24-pounder
Boxer
Hales 9-pounder
Hales 24-pounder

Machine guns

v t e British Empire naval weapons of the Victorian era
Smoothbore muzzle-loading cannons	18-pounder 24-pounder 32-pounder 55 cwt 32-pounder gun 68-pounder Somerset cannon
Smoothbore muzzle-loading shell guns	8-inch 10-inch 86 cwt
Mortars	10-inch Blomefield 13-inch Blomefield
Howitzers	12-pounder Millar 24-pounder Millar
Rifled breechloaders (Armstrong)	RBL 9 pounder RBL 20-pounder RBL 40-pounder RBL 7-inch 110-pounder
Rifled muzzle-loaders (Lancaster)	68-pounder Lancaster gun
Rifled muzzle-loaders (converted)	RML 64-pounder 71 cwt
Rifled muzzle-loaders (Woolwich)	RML 9-pounder 8 cwt RML 64-pounder 64 cwt RML 7-inch RML 8-inch RML 9-inch RML 10-inch RML 11-inch RML 12-inch 25-ton RML 12-inch 35-ton RML 12.5-inch RML 16-inch
Breech-loaders (new pattern)	BL 4-inch BL 5-inch BL 6-inch 80-pounder BL 6-inch Mk II – VI BL 8-inch BL 9.2-inch Mk I – VII BL 9.2-inch Mk VIII BL 10-inch BL 12-inch Mk I – VII BL 12-inch Mk VIII BL 13.5-inch BL 16.25-inch
Quick-firing guns	QF 3-pounder Hotchkiss QF 6-pounder Hotchkiss QF 6-pounder Nordenfelt QF 12-pounder 12 cwt Mk I QF 4-inch QF 4.7-inch QF 6-inch
Light weapons	Gatling gun Gardner gun Nordenfelt gun 1-inch Nordenfelt gun
Torpedoes	Whitehead torpedo