The QF 12 pounder 12 cwt gun was a common, versatile 3-inch (76 mm) calibre naval gun introduced in 1894 and used until the middle of the 20th century. It was produced by Armstrong Whitworth, Elswick and used on Royal Navy warships, and exported to allied countries. In British service, "12 pounder" was a rounded reference to the projectile weight and "12 cwt" referred to the weight of the barrel and breech : 12 hundredweight = 12 x 112 pounds = 1344 pounds, to differentiate it from other "12 pounder" guns.
As the Type 41 3-inch (76.2 mm)/40 it was used on most early battleships and cruisers of the Imperial Japanese Navy, though it was commonly referred to by its UK designation as a “12-pounder” gun.
United Kingdom naval service
Mk I and II guns, of "built up" construction of multiple steel layers, served on many Royal Navy destroyers up to and after World War I originally as primary and later as secondary armament against submarines and torpedo boats. They were also fitted as deck guns on D and E-class submarines.
It was estimated that out of the 4,737 Mk I and Mk II guns produced there were still 3,494 on hand for the RN in 1939. Many Mk V guns, which had a "monobloc" barrel made of a single casting, served on smaller escort ships such as destroyers and on armed merchant ships, on dual-purpose high-low angle mountings which also allowed it to be used as an anti-aircraft gun.
The gun was primarily a high-velocity naval gun, with its heavy recoil suiting it to static mountings, hence it was generally considered unsuitable for use as a mobile field gun. An exception was made when the British Army were outgunned by the Boer artillery in South Africa and the Royal Navy was called on for help. Among other guns, 16 QF 12 pounder 12 cwt were landed from warships and were mounted on improvised field carriages designed by Captain Percy Scott RN, with solid wooden trails and utilizing small-diameter Cape wagon wheels. Their 10,000-yard (9,100 m) range provided valuable long-range fire support for the army throughout the war. They were known as "long twelves" to distinguish them from the BL 12-pounder 6 cwt and QF 12-pounder 8 cwt which had much shorter barrels and ranges.
Lieutenant Burne reported that the original electric firing system, while working well under ideal conditions, required support of an armourer and the maintenance and transport of charged batteries in the field, which was generally not possible. He reported switching to percussion tubes for firing and recommended percussion for future field operations.
Another six guns were diverted from a Japanese battleship being built at Newcastle in January 1900, bought by Lady Meux and were equipped with proper field carriages by the Elswick Ordnance Company in Newcastle and sent to South Africa. Perhaps uniquely, the guns were donated directly to Lord Roberts, the British commander in South Africa and became his personal property. They were known as the "Elswick Battery" and were manned by men from Elswick, recruited by 1st Northumberland Royal Garrison Artillery (Volunteers). The Elswick guns served throughout the war.
Many guns were mounted on "pedestals" secured to the ground to defend harbours around the UK, and at many ports around the Empire, against possible attack by small fast vessels such as torpedo boats, until the 1950s. There were 103 of these guns (of a total 383 of all types) employed in coast defence around the UK as at April 1918. Many of these were still in service in World War II although they had by then been superseded by more modern types such as twin QF 6 pounder 10 cwt mounts.
Guns were traversed (moved from side to side) manually by the gunlayer as he stood on the left side with his arm hooked over a shoulder piece as he aimed, while he operated the elevating handwheel with his left hand and grasped the pistol grip with trigger in his right hand.
In World War I a number of coast defence guns were modified and mounted on special wheeled traveling carriages to create a marginally effective mobile anti-aircraft gun.
UK shells weighed 12.5 lb (5.67 kg) filled and fuzed.
The cordite propellant charge was normally ignited by an electrically-activated primer (in the base of the cartridge case), with power provided by a battery. The electric primer in the cartridge could be replaced by an adaptor which allowed the use of electric or percussion tube to be inserted to provide ignition.
The Japanese Type 41 3-inch (76 mm) naval gun was a direct copy of the QF 12 pounder. The first guns were bought from the UK firms as "Elswick Pattern N" and "Vickers Mark Z" guns. Thereafter production was in Japan under licence. It was the standard secondary or tertiary armament on most Japanese warships built between 1890 and 1920, and was still in service as late as the Pacific War.
The gun was officially designated as “Type 41” from the 41st year of the reign of Emperor Meiji on 25 December 1908. It was further re-designated in centimeters on 5 October 1917 as part of the standardization process for the Imperial Japanese Navy to the metric system. Although finally classified as an "8cm" gun the bore was unchanged at 7.62 cm.
The Type 41 3-inch naval gun fired a 12.5-pound (5.7 kg) high-explosive shell.A gun of the Elswick Battery that served in the Second Boer War is displayed in the Royal Artillery Museum, London
Another Elswick gun is with 203 (Elswick) Battery RA (V)
Mk V naval gun at Royal Artillery Museum, London
Early coast defence gun at Newhaven Fort, UK
Coast defence gun at Army Memorial Museum, Waiouru, New Zealand
On the battleship Mikasa, Yokosuka, Japan