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.
|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|
|Projectile Types and Weights||SAPC: 200 lbs. (90.7 kg)
HE: 200 lbs. (90.7 kg)
|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|
These guns were only issued 4crh projectiles.
|Elevation||Muzzle Velocity||Distance||Flight Time||Striking Velocity||Angle of Fall|
|2.5 degrees||2,700 fps (823 mps)||5,000 yards (4,570 m)||6.8 seconds||1,799 fps (548 mps)||3.3|
|7.0 degrees||10,000 yards (9,140 m)||17.3 seconds||1,218 fps (371 mps)||17.4|
|15.3 degrees||15,000 yards (13,720 m)||32.1 seconds||1,038 fps (316 mps)||32.2|
|28 degrees||20,000 yards (18,290 m)||51.1 seconds||1,071 fps (326 mps)||51.2|
|29.6 degrees||20,500 yards (18,750 m)||53.5 seconds||1,078 fps (329 mps)||53.7|
|30 degrees||21,110 yards (19,300 m)||---||---||---|
|Weight||45.975 tons (46.173 mt)|
|Elevation||-5 / +30 degrees|
|Train||about +150 / -150 degrees|
|Loading Angle||-5 to +10 degrees|
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.