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. The rammer was carried by the loading tray rocking arm. Rounds were laid in a loading tray which then was manually pushed over before the rammer could be operated and the breech closed. Springs were used for runout. A total of 84 guns were made.
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.
|Designation||4.7"/43 (12 cm) QF Mark VII
4.7"/40 (12 cm) QF Mark VIII 1
4.7"/40 (12 cm) QF Mark X
|Ship Class Used On||
|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||8 - 12 rounds per minute 2|
- ^Prefixes E and F, referring to direct electric (DEF) and electrical mechanical (EMF) firing are sometimes found in gun lists.
- ^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 these speeds.
|Weight of Complete Round||HE: 76 lbs. (34.5 kg) 12
SAP: 76 lbs. (34.5 kg)
|Projectile Types and Weights||HE: 50 lbs. (22.68 kg)
|Projectile Length||N/A - complete round 44.26 in (11.24 cm)|
|Propellant Charge 1||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 3||Nelson class: 175 rounds
Courageous class: 270 rounds
Others: 100 rounds
- ^By the end of the war flashless charges were issued and in the Nelson class half of the HE were to have VT fuzes.
- ^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).
- ^Outfits for smaller ships included SAP and HE but the Nelson class did not carry SAP. 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.
|Weight||27,692 lbs. (12,561 kg)|
|Elevation||HA Mark XII: -5 / +90 degrees 3
CPXV: -5 (?) / +50 degrees
|Elevation Rate 4||HA Mark XII: 10 degrees per second
CPXV: Manually worked, only
|Train Rate 4||10 degrees per second
CPXV: Manually worked, only
|Gun recoil||18 in (46 cm)|
Each HA mounting had a fuze setter on the left side.
- ^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.
- ^HMS Rodney had one mounting with rack type rammer gear, which limited elevation to 77 degrees.
- ^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.
- "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