RML 7-inch Armstrong Gun
| Company type | Company |
|---|---|
| Industry | Artillery manufacturing |
| Founded | January 1, 1859 |
| Founder | William Armstrong, 1st Baron Armstrong |
| Headquarters | Newcastle , United Kingdom |
| Products | Artillery pieces, including RML 7-inch Armstrong Gun |
The RML 7-inch Armstrong Gun was a rifled muzzle-loading artillery piece. This model represented an export variant of the British Royal Navy's own RML 7-inch gun. Production was carried out by the Elswick Ordnance Company, established by William Armstrong, 1st Baron Armstrong.
The Armstrong gun
In 1859, the United Kingdom introduced rifled breechloading artillery known as Armstrong guns, engineered by William Armstrong, 1st Baron Armstrong, who subsequently became the chief engineer for rifled ordnance.[1] These guns were manufactured both at the Royal Works located in Woolwich and at the newly founded Elswick Ordnance Company in Newcastle, which opened on January 1, 1859 with government backing.[2] This arrangement ensured a clear division between Armstrong's official duties as a civil servant and his business interests as an industrialist.
For naval use, Armstrong's breechloaders were available in calibers of 4.75 inch (40-pounder), 6.4 inch (70-pounder), and 7 inch (110-pounder). After certain adjustments, the guns up to and including the 40-pounder caliber demonstrated strong performance in both trials and combat.[3] During the 1863 Bombardment of Kagoshima, eight of the 110-pounder guns were deployed effectively. Although these larger guns occasionally experienced operational difficulties,[4] issues related to the wedge breech mechanism were ultimately resolved satisfactorily.[5]
Woolwich artillery pieces
The Battle of Hampton Roads in March 1862 highlighted the significant challenge of breaching a ship's armor. By 1864, a comparative evaluation was conducted involving three variants of 70-pounder guns. During this assessment, Armstrong recommended limiting the powder charge in his breechloader to no more than 9 pounds. In contrast, the other weapons examined—the Armstrong muzzle-loading gun and the Whitworth muzzle loader—utilized 14 and 12 pounds of gunpowder respectively, to discharge projectiles weighing approximately 70 pounds. Despite these substantial charges, achieving effective penetration remained problematic. Consequently, the Royal Navy shifted its focus toward muzzle-loading rifled artillery.
These newly developed muzzle-loading pieces became known as Woolwich guns. Although Armstrong had enhanced the Royal Artillery facilities at Woolwich for producing his breechloading guns, he departed from his position in 1863. Subsequently, the Woolwich Works commenced manufacturing rifled muzzle loaders (RMLs). These guns incorporated Armstrong's barrel fabrication techniques, and initial RML models also employed his shunt rifling principle. This association sometimes led to these weapons being loosely identified as Armstrong guns; however, they were not produced by Armstrong's own firm—later recognized as Elswick Ordnance Company—part of Armstrong's enterprise. In 1865, Woolwich introduced 7- and 9-inch RMLs employing a novel rifling design known as the Woolwich system, which is why these artillery pieces earned the designation Woolwich guns.
The Armstrong RML (specific gun type)
While the Royal Navy manufactured its own artillery at Woolwich, Armstrong’s Elswick Ordnance Company in Newcastle was reintegrated into the Armstrong company. Elswick continued producing heavy artillery exclusively for export markets. Among these was a 7-inch RML gun, which was identified by the Dutch and others as an 18 cm Armstrong gun. Thus, when foreign users mentioned an Armstrong gun, they implied it was produced by Armstrong at Elswick. In Britain, however, referring to a gun simply as an 'Armstrong gun' without specifying 'Muzzle Loading' was not feasible because domestically that term denoted a particular type of weapon rather than the manufacturer.
Size and caliber
The overall specifications of the RML 7-inch Armstrong Gun—including its length and caliber—matched those of the 7-inch Woolwich gun. Within the Royal Navy, the 7-inch Woolwich gun was introduced in 1865 for use as either broadside or pivot-mounted armament on frigates. Simultaneously, the 9-inch Woolwich model became the principal artillery piece for heavily armored ironclads.
Construction coils
A notable distinction between the Armstrong-made RML and the Woolwich guns lay in their coil construction. Coils consisted of wrought iron components tightly fitted around a steel inner tube to reinforce it against bursting from firing pressures. The Armstrong variant retained a greater number of smaller coils—a design choice that increased production costs. Visually, these coils appear as raised sections that taper toward the front of the barrel.
The Rijksmuseum’s model of the RML 7-inch Armstrong Gun displays five coils, whereas photographic evidence of the RML 7-inch Woolwich Mark I reveals one additional coil. The Rijksmuseum artifact also illustrates coil reinforcement at the rear portion of the barrel.
Grooves
The Dutch navy's version of the RML 7-inch Armstrong Gun featured a rifling pattern consisting of only three grooves.
In Chile, this weapon was referred to as the cañón giratorio de 115 libras (rifled 115-pounder) and was chosen as the primary armament for the Chilean Navy corvette Magallanes.
Initially, the Dutch navy depended on domestically developed rifled guns such as the RML 16 cm No. 3. When establishing an armored fleet for coastal defense, they opted for the RML 9-inch Armstrong Gun as their principal weapon, mirroring the Royal Navy’s early use of the RML 9-inch 12-ton gun.
For unarmored steam frigates and corvettes, the Dutch continued to deploy 16 cm RML guns at first. However, in 1869 they introduced the RML 7-inch Armstrong Gun to equip certain unarmored vessels, predominantly gunvessels tasked with patrolling Dutch East Indies waters, including ships from the Pontianak-class gunvessel series.
Dutch ammunition
-
Hardened Palliser shell MK III for 7 inch RML -
Common shell MK V for 7 inch RML -
Likely Boxer Shrapnel Mk II for 7 inch RML -
18 cm segment shell stored in wooden crate
The Dutch arsenal included two varieties of pointed iron grenades (puntgranaat) designed for the 7-inch Armstrong gun: a standard iron grenade measuring 51.6 cm in length and weighing 48.75 kg, and a hardened variant measuring 41 cm with a weight of 51.5 kg.
Additionally, there existed a substantial 'pointed bullet' (puntkogel) that was 38 cm long and weighed 52.5 kg. The ammunition types also comprised a shrapnel round containing an assortment of large and small projectiles, with a total weight of 31 kg.
Notes
- ↑ Heald 2011, p. 75.
- ↑ Heald 2011, p. 77.
- ↑ Armstrong & Whitworth Committee 1866, p. 17.
- ↑ Armstrong & Whitworth Committee 1866, p. 16.
- ↑ Armstrong & Whitworth Committee 1866, p. 111.
References
- Armstrong & Whitworth Committee (1866). The Report of the Armstrong & Whitworth Committee. Joseph Thomson & Son, Manchester.
- Brassey, Thomas (1882). The British Navy: Its Strength, Resources, and Administration. Vol. II. Longmans, Green and Co.
- Haakman, J.H. (1872). Handboek over de zee-artillerie voor konstabels en matrozen-kanonniers. J.C. de Buisonjé, Nieuwediep.
- Heald, Henrietta (2011). William Armstrong: Magician of the North. McNidder and Grace Limited.
- Owen, J.F. (1877). Treatise on the Construction and Manufacture of Ordnance in the British Service prepared in the Royal Gun Factory. Clowes and Sons.
- Swart, Jacob (1869). "VII Iets over het tegenwoordige zware Geschut." Verhandelingen en Berigten Betrekkelijk Het Zeewezen, Vol. XXVIII. Wed. G. Hulst van Keulen.
- Tideman, B.J. (1880). Memoriaal van de Marine. Van Heteren Amsterdam.