Britain
4.7"/43 (12 cm) QF Mark VII
4.7"/40 (12 cm) QF Mark VIII
4.7"/40 (12 cm) QF Mark X
Updated 29 August 2014

The 4.7"/43 (12 cm) Mark VII was a fixed-ammunition AAA gun developed late in World War I.  Only four guns were made and these did not enter service.  Performance was said to similar to that of the 4.7"/40 (12 cm) QF Mark VIII.  It had been planned to fit the "A" class Flotilla Leader HMS Codrington with these guns, but this was cancelled and she commissioned with an outfit of 4.7"/45 (12.7 cm) Mark IX guns.

The 4.7"/40 (12 cm) QF Mark VIII was originally developed as an AAA weapon for the "G3" and "N3" capital ships of 1920.  When those ships were cancelled as a result of the Washington Naval Limitation Treaty, these weapons were then mounted on the Nelson class battleships and on converted carriers.  This was the largest caliber fixed-ammunition gun ever to enter service in the Royal Navy, although the rounds for these guns were lighter and shorter than the fixed rounds developed for the later 4.5" (11 cm) guns.

The fixed round for this weapon weighed a total of 74 lbs. (33.6 kg).  During service evaluation, it was found that this weapon could not maintain a high rate of fire - a necessity for an AA weapon - as the heavy round rapidly wore out the gun crews.

The Mark VII was constructed of a tapered inner A tube, A tube, full length wire, jacket and breech ring.  Used a horizontal sliding breech mechanism that was hand operated but opened automatically after firing.

The Mark VIII was constructed of a tapered inner A tube, A tube, part length wire, jacket and breech ring.  Used a horizontal sliding breech mechanism that was hand operated but opened automatically after firing.  The mounts were unusual for British guns in having a power rammer, which allowed faster firing at high elevations.  However, the shell had to be laid in a loading tray which then had be manually pushed over before the automatic rammer operated and the breech closed.

The 4.7"/40 (12 cm) Mark X was a separate ammunition version of the 4.7" (12 cm) Mark VIII.  Only one of these guns was ever built and it was used for a few years on the submarine HMS Perseus in a 50 degree CPXV mounting.

All British 4.7" guns have an actual bore diameter of 4.724" (12 cm).

The data that follows is specifically for the Mark VIII except where noted.

WNBR_47-40_mk8_Rodney_guncrew_pic.jpg

Loading a 4.7"/40 (12 cm) Mark VIII on HMS Rodney
Note the position of the counterweight and how tight were the working conditions at this training angle
In the background are an octuple pom-pom and a 6"/50 (15.2 cm) turret
IWM photograph A 87

WNBR_47-40_mk8_Rodney_pic.jpg

4.7"/40 (12 cm) QF Mark VIII on HMS Rodney
Note the large elevation arc and the lack of gun shields which were not fitted until 1940
IWM photograph A 88

WNBR_47-40_mk8_Rodney_amidships_pic.jpg

4.7"/40 guns on HMS Rodney in 1943
Note that shields are now fitted to the 4.7" (12 cm) guns
IWM Photograph A 16074

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Gun Characteristics
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Designation 4.7"/43 (12 cm) QF Mark VII
4.7"/40 (12 cm) QF Mark VIII  (see Note 1)
4.7"/40 (12 cm) QF Mark X
Ship Class Used On Mark VII:  N/A
Mark VIII:
   Nelson and Courageous classes
   Albatross and Adventure
Mark X:  Submarine Perseus
Date Of Design Mark VII:  about 1918
Mark VIII:  1925
Mark X:  about 1930 (?)
Date In Service Mark VII:  Not in service
Mark VIII:  1926
Mark X:  about 1931 (?)
Gun Weight Mark VII:  7,560 lbs. (3,429 kg)
Mark VIII:  6,636 lbs. (3,010 kg)
Mark X:  N/A
Gun Length oa 197 in (5.004 m)
Bore Length 189 in (4.800 m)
Rifling Length 161.7 in (4.108 m)
Grooves (38) 0.037 in deep x 0.270 (0.94 x 6.86 mm)
Lands 0.1205 in (3.061 mm)
Twist Uniform RH 1 in 30
Chamber Volume Mark VII:  475 in3 (7.78 dm3)
Mark VIII:  454 in3 (7.44 dm3)
Mark X:  N/A
Rate Of Fire
(see Note 2)
8 - 12 rounds per minute
Notes:

1) Prefixes E and F, referring to direct electric (DEF) and electrical mechanical (EMF) firing are sometimes found in gun lists.

2) The fastest practical firing cycle was about 5 seconds.  Faster cycle times were recorded with 15 rounds per minute being the highest, but the rammers became unreliable at those speeds.

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Ammunition
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Type Fixed
Weight of Complete Round HE - 76 lbs. (34.5 kg)
Illum - N/A
Smoke - N/A
Projectile Types and Weights HE - 50 lbs. (22.68 kg)
Illum - N/A
Smoke - N/A
Bursting Charge N/A
Projectile Length N/A - complete round 44.26 in (11.24 cm)
Propellant Charge 9.34 lbs. (4.24 kg) MC19
10.19 lbs. (4.63 kg) SC103
10.94 lbs. (4.96 kg) NF/S 164-048
Cartridge - 26 lbs. (11.82 kg)
Muzzle Velocity 2,457 fps (749 mps)
Working Pressure 20.5 tons/in2 (3,230 kg/cm2)
Approximate Barrel Life 1,050 - 1,200 rounds
Ammunition stowage per gun Nelson class:  175 rounds
Courageous class:  270 rounds
Others:  100 rounds
Notes:

1) Outfits included SAP and HE but the Nelson class did not carry SAP.

2) By the end of the war flashless charges were issued and in the Nelson class half of the HE were to have VT fuzes.

3) Outfit for Nelson class was 175 HE per gun plus 150 Star Shell and 20 target smoke rounds per ship.  Star Shell allowance was upped to 400 rounds during World War II.

4) In 1931 it was estimated that the HE shell for this gun against aircraft had a lethal volume 33 feet long by 78 feet in diameter (10 x 24 m).

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Range
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Elevation With 50 lbs. (22.7 kg) HE Shell
Range @ 45 degrees 16,160 yards (14,780 m)
AA Ceiling 32,000 feet (9,750 m)
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Mount / Turret Data
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Designation Open Single Mounting
   Codrington (1):  HA Mark XI
   Nelson (6), Courageous (16) and Albatross (4):  HA Mark XII
   Perseus (1):  CPXV
Weight  27,692 lbs. (12,561 kg)
Elevation HA Mark XII:  -5 / +90 degrees
CPXV:  -5 (?) / +50 degrees
Elevation Rate HA Mark XII:  10 degrees per second
CPXV:  Manually worked, only
Train 360 degrees
Train Rate 10 degrees per second
CPXV:  Manually worked, only
Gun recoil 18 in (46 cm)
Notes:

1) HMS Rodney had one mounting with rack type rammer gear, which limited elevation to 77 degrees.

2) Some mountings had simple shields added and an armored "zareba" was fitted around the 4.7" (12 cm) gun decks on Nelson and Rodney in 1940.

3) The HA mountings had a 9 hp electric motor and hydraulic pump to provide elevation and training.  This provided about twice the speed of manual training and elevation.

4) Perseus was later fitted with the standard 4"/40 (10.2 cm) submarine gun.

5) Each HA mounting had a fuze setter on the left side.

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Data from
"Nelson to Vanguard:  Warship Design and Development 1923-1945" by D.K. Brown
"Naval Weapons of World War Two" and "British Naval Guns 1880-1945 No 15" article in "Warship Volume IX" both by John Campbell
"British Carrier Aviation" by Norman Friedman
"British Battleships of World War Two" by Alan Raven and John Roberts
"Destroyers of World War Two" by M.J. Whitley
Page History

31 December 2006 - Benchmark
12 February 2012 - Updated to latest template
15 December 2013 - Added photograph of Rodney amidships
29 August 2014 - Added photograph of guncrew and note about fuze setter