Britian 6"/40 (15.2 cm) QF Marks I, II and III

Britian
6"/40 (15.2 cm) QF Marks I, II and III
Updated 27 June 2008

These guns were used on most pre-dreadnoughts and cruisers built between 1890 and 1905. The Mark I and Mark II were only slightly different in construction and are normally listed together in armament lists. Mark III was a trunnioned version of the Mark I.

Mark I was EOC Pattern "Z" and was of built up construction while Mark II was a Woolwich design. The Mark III was known to EOC as "Z¹." All used a 3-motion breech mechanism but most were later converted to a single motion breech mechanism. Guns so converted had a "B" added after the Mark number. A total of 137 Mark I, 760 Mark II and 53 Mark III guns were made. Some of these guns were employed as AA weapons during World War I, but this did not prove very successful. 63 Mark II guns were transferred to the Army, where they were bored out and converted to 8" (20.3 cm) howitzers.

Nomenclature note: The 6"/45 (15.2 cm) QF Mark IV designation was given to twelve guns purchased from the USA firm of Bethlehem Steel early in World War I. Eight of these were used in coastal defenses at Scapa Flow and four were used on DAMS. These guns may actually have been the Bethlehem 6"/44 (15.2 cm) Mark 9 or a close relation.

HMS Furious in 1898
6"/40 (15.2 cm) gun in bow pedestal mount
U.S. Naval Historical Center Photograph # NH 61062

6"/40 (15.2 cm) guns on HMS Hermes
The original postcard is titled "Captain Scott's Dotter" which was a mechanism used to teach gunsighting techniques
Photograph courtesy of Brian Cave and Paul Benyon

. Images at The Vickers Photographic Archive

See photograph 6487

Gun Characteristics .

Designation	6"/40 (15.2 cm) QF Marks I, III and III
Ship Class Used On	Pre-dreadnoughts Royal Sovereign, Hood, Renown, Majestic and Canopus classes Armored cruisers Diadem, Powerful, Royal Arthur and Edgar classes Small cruisers Blake, Aeolus, Brilliant, Iphigenia, Hermes, Challenger, Arrogant, Eclipse and Astraea classes Rearmed Ships Indefatigable, Intrepid, Rainbow and Sirius Added to Hercules, Immortalité and Narcissus During World War I these guns were used on most large monitors and many AMCs and DAMS These guns were used as secondaries on the Italian Garibaldi class armored cruisers, with the Argentine cruisers Pueyrredon and Admiral Belgrano using Mark II guns
Date Of Design	1888
Date In Service	1892
Gun Weight	6.6 tons (6.7 mt)
Gun Length oa	249.25 in (6.331 m)
Bore Length	240.0 in (6.096 m)
Rifling Length	N/A
Grooves	N/A
Lands	N/A
Twist	N/A
Chamber Volume	832 in³ (13.63 dm³)
Rate Of Fire	5 - 7 rounds per minute

Ammunition .

Type	Separate
Projectile Types and Weights	CPC - 100 lbs. (45.3 kg) HE - 100 lbs. (45.3 kg)
Bursting Charge	N/A
Projectile Length	26.5 in (67.3 cm)
Propellant Charge	29.75 lbs. (13.49 kg) EXE 13.25 lbs. (6.01 kg) Cord 30 15.94 lbs. (7.23 kg) MD26
Muzzle Velocity	EXE - 1,882 fps (574 mps) Cord - 2,230 fps (670 mps) MD - 2,243 fps (684 mps)
Working Pressure	N/A
Approximate Barrel Life	N/A
Ammunition stowage per gun	N/A
Note: Projectiles were 2crh.

Range .

Elevation	With 100 lbs. (45.36) HE Shell
Range @ 15 degrees	With Cord 30 - 10,000 yards (9,140 m)

Mount / Turret Data .

Designation	Single Mounts: CPI and PII
Weight	N/A
Elevation	CPI Deck mountings: -3 / +20 degrees Casemate mountings: -3 / +15 degrees PII Deck mountings: -3 / +19 degrees Casemate mountings: -3 / +15 degrees AA mountings -3 / +53.5 degrees
Elevation Rate	Manual operation, only
Train	about +30 / +150 degrees in casemate mountings about -150 / +150 degrees in open mountings
Train Rate	Manual operation, only
Gun recoil	N/A
Note: A total of four CPI and twelve PII mountings were converted for AA use.

Data from
"Big Gun Monitors: The History of the Design, Construction and Operation of the Royal Navy's Monitors" by Ian Buxton
"Naval Weapons of World War Two" and "British Naval Guns 1880-1945 No 11" article in "Warship Volume VII" both by John Campbell
"British Battleships: 1860 - 1950" by Oscar Parkes