Britain
7.5"/45 (19 cm) Mark VI
Updated 18 February 2009
These guns were used mainly on the Hawkins class cruisers which were intended for the anti-merchant cruiser and trade protection roles.  In order to give sufficient deck clearance for the recoil at full elevation, the center-line guns were mounted in shallow wells and the side weapons were mounted on elevated platforms.  This gun and its projectiles were rather heavy for use in a simple, open mount and proved somewhat cumbersome in service.

  A total of 44 guns were manufactured.  As the Hawkins class were gradually converted to other weapons during their careers, many of these guns became surplus to naval requirements and 17 were then transferred to coastal artillery.  Three were at South Shields between July 1941 to August 1943, seven went to the Dutch West Indies, three to Canada and five to Mozambique.  However, two of the guns intended for Mozambique were lost in transit in 1943.  These were replaced by transferring two guns from South Shields.

The ballistic performance of the Mark V was about the same as the earlier 7.5" (19 cm) Mark I, but they were of improved construction, being of tapered inner A tube, A tube, full-length wire, full-length jacket breech ring, shrunk collar and breech bush.  They also had a different form of rifling and used Asbury breech mechanisms.
WNBR_75-45_mk6_Hawkins_pic.jpg

HMS Hawkins moored at Shanghai, China, about 1927
U.S. Naval Historical Center Photograph # NH 105067-A
Click on this picture for a larger image
WNBR_75-45_mk6_Frobisher_pic.jpg

HMS Frobisher in 1945
Converted to a training ship in 1942, she still retained her bow 7.5" (19 cm) gun
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Gun Characteristics
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Designation 7.5"/45 (19 cm) Mark VI
Ship Class Used On Vindictive and Hawkins classes
Date Of Design 1915
Date In Service 1919
Gun Weight 13.789 tons (14.010 mt)
Gun Length oa 349.2 in (8.870 m)
Bore Length 337.5 in (8.573 m)
Rifling Length 278.5 in (7.074 m)
Grooves (44 or 45) 0.0555 in deep x 0.380 (1.41 x 9.65 mm)
Lands 0.1555 or 0.1436 in (3.95 or 3.647 mm)
Twist Uniform RH 1 in 30
Chamber Volume 4,500 in3 (73.70 dm3)
Rate Of Fire 5 - 6 rounds per minute
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Ammunition
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Type Bag
Projectile Types and Weights SAPC - 200 lbs. (90.7 kg)
HE - 200 lbs. (90.7 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 61.9 lbs. (28.1 kg) SC150
Muzzle Velocity 2,770 fps (844 mps)
Working Pressure 20.5 tons/in2 (3,230 kg/cm2)
Approximate Barrel Life 650 rounds
Ammunition stowage per gun 150 rounds
Note:  These guns were only issued 4crh projectiles.
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Range
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Elevation With 200 lbs. (90.7 kg) SAPC Shell
MV of 2,700 fps (823 mps)
Striking Velocity
Angle of Fall
2.5 degrees 5,000 yards (4,570 m)
1,799 fps (548 mps)
3.3
7.0 degrees 10,000 yards (9,140 m)
1,218 fps (371 mps)
17.4
15.3 degrees 15,000 yards (13,720 m)
1,038 fps (316 mps)
32.2
28 degrees 20,000 yards (18,290 m)
1,071 fps (326 mps)
51.2
29.6 degrees 20,500 yards (18,750 m)
1,078 fps (329 mps)
53.7
30 degrees 21,110 yards (19,300 m)
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Note:  Time of flight for SAPC Shell with MV = 2,700 fps (823 mps)
     5,000 yards (4,570 m):  6.8 seconds
   10,000 yards (9,140 m): 17.3 seconds
   15,000 yards (13,720 m):  32.1 seconds
   20,000 yards (18,290 m):  51.1 seconds
   20,500 yards (18,750 m):  53.5 seconds
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Mount / Turret Data
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Designation Single Mounts
   Hawkins (7) and Vindictive (4):  CP Mark V (Half shield, only)
Weight  45.975 tons (46.173 mt)
Elevation -5 / +30 degrees
Elevation Rate N/A
Train about +150 / -150 degrees
Train Rate N/A
Gun recoil N/A
Loading Angle -5 to +10 degrees
Notes:  This mounting was essentially a hand-worked center pivot type with additional power training and elevation provided by a 10 HP electric motor and hydraulic pump.  Run-out was spring-powered.
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Data from
"Naval Weapons of World War Two" and "British Naval Guns 1880-1945 No 9" article in "Warship Volume VII" both by John Campbell
"British Cruisers of World War Two" by Alan Raven and John Roberts
"Cruisers of World War Two" by M.J. Whitley
Page History

05 December 2007 - Benchmark
18 February 2009 - Minor typographical fix