QF 4.7-inch Mk I–IV naval gun

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QF 4.7-inch Mk I–IV naval gun: a short, easy-to-understand overview

What it is
- A family of British quick-firing naval and coastal guns, about 4.7 inches (120 mm) in diameter.
- Used from the late 1880s into the 20th century on warships, coastal defences, and even land carriages for army use.
- The marks (Mk I–IV) refer to early versions, with Mk IV introducing a heavier, wire-wound construction.

How it was made and why it was special
- Built by the Elswick Ordnance Company (part of Armstrong Whitworth).
- Sought to exploit the new Quick-Firing (QF) technology: a brass-case cartridge with an integrated base primer. This let the gun be loaded and fired faster than the older bagged-charge breech system.
- The gun’s barrel length was 40 calibres (the bore length is 40 times the bore diameter), and early versions used a three-motion breech. The Mk IV added a wire-wound construction for extra strength.
- The guns fired a 45-pound (about 20 kg) shell and could be mounted on ship masts, coast-defence mounts, or mobile army carriages.

Key specifications
- Calibre: 4.724 inches (120 mm).
- Barrel length: 40 calibres.
- Typical shell weight: 45 pounds (20.4 kg).
- Rate of fire: about 5–6 rounds per minute.
- Muzzle velocity: about 544–660 m/s depending on the propellant.
- Maximum firing range: roughly 8,000–12,000 yards (about 7.3–11 km) depending on elevation and carriage.

Who used it
- United Kingdom: both the Royal Navy and the Army used the gun in different forms. Many were assigned to pre-dreadnoughts and cruisers, with army batteries later converting them for coastal or field use.
- Other nations also bought or licensed the design, sometimes under different names or markings.

Design and development in brief
- The first in the line emerged as Pattern M in the 1880s, designed to replace older 5-inch naval guns.
- Early models were refined into Mk I–IV by Elswick, meeting the needs of metric-sized navies (hence the common approximation of 4.7 inches as the British designation).
- Army field carriages (Percy Scott carriage) allowed the same gun to serve on land for long-range fire; these setups lacked modern recoil buffers at first, requiring careful handling.
- The Mk IV introduced a wire-wound design for added strength, while some guns were later equipped with a single-motion breech or reworked as A/B subtypes.

United Kingdom service and use
- Production numbers were substantial: Mk I, II, III, and IV were produced in large quantities for naval and coastal use; the Royal Navy received many directly, and the Army supplied additional guns for coast defence and land batteries.
- By World War I, the 4.7-inch guns were obsolete for frontline warship work but remained useful for defence of ships, merchant vessels, and troop transports, as well as coastal batteries.
- The guns saw action in various theaters, including early Western Front battles, Gallipoli, and in colonial and coastal operations. In some cases, they were employed on improvised or converted carriages due to evolving artillery technology.

World War I and related campaigns
- South-West Africa Campaign (1914–1915): guns mounted on Percy Scott carriages were used by South African forces against German forces.
- Western Front (1914–1917): the 4.7-inch guns were deployed with Royal Garrison Artillery units and on some improvised carriages; they faced wear and the growing advantage of longer-range, heavier guns. They fought at Neuve Chapelle and Aubers Ridge, among other actions.
- By 1916–1917, these guns were largely superseded by more modern 60-pounder and other larger-calibre weapons. Some remained in service on other fronts or in secondary roles until the end of the war or early postwar period.

Licensed products and overseas use
- Italy: licensed versions were produced as 120/40 A 1889 and 120/40 A 1891 by Ansaldo, used on a variety of ships, including cruisers and dreadnoughts.
- Japan: license-built copies known as Type 41 (Mark IV origin) and Mark IVJ; used on Japanese cruisers and later appearing in other roles. Some were supplied to Britain during World War I as part of Allied aid; later used in coastal batteries in World War II.
- United States: the U.S. Army bought British QF 4.7-inch guns in the late 1890s and designated them 4.72-inch Armstrong guns. They served in coastal defence batteries and on transports during WWI; a few were retired or replaced by 5-inch guns after modernization. A small number were preserved or displayed as memorials.

Ammunition and loading
- The gun used fixed Quick-Firing ammunition, a complete round weighing about 45 pounds (20.4 kg).
- Shell types included armor-piercing, high-explosive, common, shrapnel, and illumination rounds.
- Fixed rounds simplified loading and improved rate of fire compared with earlier bagged charges.

Surviving examples
- A number of 4.7-inch Mk I–IV guns survive in museums and on display around the world, including examples in Spain, Canada, the United States, and Finland. Some are mounted on restored carriages, others are shown as standalone guns or in coastal defense settings.

In summary
The QF 4.7-inch Mk I–IV was a versatile British 120 mm, quick-firing gun developed in the late 19th century to provide faster, more reliable naval and coastal firepower. It served the UK and several export customers in ships, coast defenses, and land batteries, and influenced later designs through its quick-firing concept and adaptable carriage configurations. Although largely superseded by larger, more modern artillery in World War I, the gun played a notable role in late 19th- and early 20th-century warfare and left a lasting mark on naval and coastal artillery development.