| Ordnance RBL 7-inch gun | |
|---|---|
 A gun on a wooden slide carriage in the 19th century. | |
| Type |
|
| Place of origin | United Kingdom |
| Service history | |
| In service | 1861–190? |
| Used by | United Kingdom |
| Wars | |
| Production history | |
| Designer | W. G. Armstrong Co. |
| Manufacturer | |
| Unit cost | £425–£650[1] (equivalent to £47000–£72000 in 2013) |
| Produced | 1859–1864 |
| No. built | 959[2] |
| Variants | 82cwt, 72cwt |
| Specifications | |
| Barrel length | 99.5 inches (2.527 m) bore (14.21 calibres)[3] |
| Shell | 90 to 109 pounds (40 to 50 kg)[4] |
| Calibre | 7-inch (177.8 mm)[3] |
| Breech | Armstrong screw with vertical sliding vent-piece (block) |
| Muzzle velocity | 1,100 feet per second (340 m/s)[3] |
| Maximum firing range | 3,500 yards (3,200 m)[5] |
The Armstrong RBL 7-inch gun, also known as the 110-pounder,[4] was a heavy caliber Armstrong gun, an early type of rifled breechloader.
William Armstrong's innovative combination of a rifled built-up gun with breechloading had proven suitable for small cannon. When it was applied to a 7-inch gun, it proved that the pressure caused by the explosive charge that was required to propel a 110-pound shot was too much for his breechloading system.
- ^ £424/13 shillings Royal Gun Factory (Woolwich) production cost 1859–1862; £650 Elswick Ordnance (Armstrongs) production cost 1862–63. Report of the Select Committee on Ordnance 1862. The gun was not sold commercially, hence a sale price is not available. Quoted in Holley 1865, pages 25–26
- ^ 959 were in service in 1877 : 883 82cwt & 76 72cwt. Quoted in Treatise on Manufacture of Ordnance 1877, page 150. Holley 1865, page 13 quotes 799 as at 1863 : 179 manufactured by Elswick Ordnance and 620 by the Royal Gun Factory. From the Report of the Select Committee on Ordnance, 1863.
- ^ a b c 1100 ft/sec firing 109 pound projectile with 11lb RLG2 (gunpowder). Text Book of Gunnery 1887, Table XVI page 313
- ^ a b The gun was originally a "100-pounder". In 1861 the projectile weight was increased to 110-pound and this became standard and was used to describe the gun. In 1865 a "light" shell of 90 lb was adopted for naval service for the 82 cwt gun only, to reduce recoil. The light shell was unsuitable for the 72 cwt gun as its reduced 10 lb charge with the light shell was insufficient to break up and distribute the lubricator in the bore (Treatise on Ammunition 1877, page 153). The gun's later official designation was "7-inch" (Treatise on Manufacture of Ordnance 1877, page 154). 109 lb projectile is given in Text Book of Gunnery, 1887. The 1902 Text Book of Gunnery refers only to a 100 lb shell for both 72 cwt and 82 cwt guns.
- ^ Text Book of Gunnery, 1902