| RML 7-inch gun | |
|---|---|
 7-inch 6½ ton Mk I gun and crew on HMS Minotaur | |
| Type | Naval gun Coast defence gun |
| Place of origin | United Kingdom |
| Service history | |
| Used by | Royal Navy |
| Production history | |
| Designer | Royal Gun Factory |
| Designed | 1865 (7 & 6½ ton) 1874 (90 cwt) |
| Manufacturer | Royal Arsenal |
| Unit cost | £425[1] |
| Variants | 7 ton Mks I – IV 6½ ton Mks I – III 90 cwt |
| Specifications | |
| Barrel length | 7 ton : 126 inches (3,200 mm) 6½ ton & 90 cwt : 111 inches (2,800 mm)[2] |
| Shell | 112 to 115 pounds (51 to 52 kg) Palliser, Common, Shrapnel[3] 160 pounds (73 kg) double common shell |
| Calibre | 7-inch (177.8 mm) |
| Muzzle velocity | 7 ton : 1,561 feet per second (476 m/s) 6½ ton : 1,525 feet per second (465 m/s) 90 cwt : 1,325 feet per second (404 m/s) |
| Maximum firing range | 5,500 yards (5,000 m) |
The RML 7-inch guns were various designs of medium-sized rifled muzzle-loading guns used to arm small to medium-sized British warships in the late 19th century, and some were used ashore for coast defence.
- ^ Unit cost of £424 11 shillings 10 pence is quoted for the 7-inch 6½ ton gun in "The British Navy" Volume II, 1882, by Sir Thomas Brassey. Page 38
- ^ Treatise on construction of ordnance in the British service, 1877, Table XXIX
- ^ Treatise on Ammunition 1877 and Treatise on construction of ordnance in the British service, 1877 describe a 115-pound projectile; Text Book of Gunnery 1887 and Brassey's Naval Annual 1888 describe a 112-pound 1 oz projectile. 112 lb 1 oz appears to be the weight of the empty Palliser shell i.e. without gunpowder filling which was typically 2 lb 10 oz. By 1887 palliser shell had been discontinued and existing shell converted to shot by removing the gunpowder – hence old Palliser ammunition would then be 112 lb 1 oz.