Description

A Bofors design, these guns were developed during the 1940s as an intermediate weapon between the 6"/50 (15.2 cm) and the 5.7 cm/60. Used on Swedish, Dutch and Colombian ships.

Employs a pendulum loader and a flick rammer to obtain a high rate of fire. After ramming, the shell separates from the cartridge. Bofors claims that this unusual process decreases barrel wear and also retains the cartridge case firmly in place until the vertical-sliding breechblock has closed. Guns are in a common cradle and barrels have water cooling jackets.

Netherlands guns were assembled by Wilton-Fijenoord.

This mount was considered to be extremely advanced when it first appeared in 1950 and the Swedish Navy was quite happy with this weapon system on their ships. The Netherlands Navy found them to be very reliable once some early training problems were overcome. However, when inspected by the British in 1953, it was rejected as being too heavy, too noisy and not gas- or flash-tight.

Gun Characteristics

Designation Sweden: 120 mm/50 (4.7") Model 1950
Netherlands: 120 mm/50 (4.7") Mark 10
Ship Class Used On Netherlands
   Holland, Friesland and Tromp Classes 1

Sweden
   Halland Class

Colombia
   20 de Julio Class (ex-Halland Class)

Peru
   Colonel Bolognesi Class (ex-Friesland Class)

Date Of Design 1944 - 1950
Date In Service 1950
Gun Weight N/A
Gun Length 251.5 in (6.387 m)
Bore Length 236.2 in (6.000 m)
Rifling Length N/A
Grooves (36)
Lands N/A
Twist Uniform RH 1 in 27
Chamber Volume N/A
Rate Of Fire Selectable between 12 and 42 rounds per minute
(42 gives the optimum dispersion)
  • ^The Tromp class frigates were armed with guns and mountings salvaged from HNLMS Gelderland, a Holland class destroyer.

Ammunition

Type Fixed
Weight of complete round HE: 97.9 lbs. (44.4 kg)
SAP: 97.9 lbs. (44.4 kg)
Illumination: N/A
Projectile Types and Weights HE: 51.8 lbs. (23.5 kg)
SAP: 51.8 lbs. (23.5 kg)
Illumination: N/A
Bursting Charge HE: 4.9 lbs. (2.2 kg)
SAP: 0.9 lbs. (0.4 kg)
Projectile Length All: 33.5 in (85 cm)
Propellant Charge 16.1 lbs. (7.3 kg)
Muzzle Velocity 2,789 fps (850 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun Netherlands: 1,600 rounds
Others: N/A

Range

Range with 51.8 lbs. (23.5 kg) HE
Elevation Distance
45 degrees 22,420 yards (20,500 m)
AA Ceiling about 9,800 feet (9,000 m)

Mount/Turret Data

Designation Twin Turrets
   Netherlands: Holland (2), Friesland (2) and Tromp (1)
   Sweden: Halland (2)
Weight 114,600 lbs. (52,000 kg) 1a
Elevation -10 / +85 degrees
Elevation Rate 40 degrees per second
Train +140 / -140 degrees maximum
Train Rate 25 degrees per second
Gun recoil 20.5 in (52 cm) 2a
  • ^The mountings originally weighed about 147,700 lbs. (67,000 kg). This was reduced to the above figure by removing the emergency diesel engine, the fuze setting mechanisms and the local fire control equipment.
  • ^The maximum, metal to metal recoil distance was 21.7 inches (55 cm).
  • The mount was crewed by 12 men of which 5 are in the turret, 2 in the elevator and 5 in the munition stowage.

Additional Pictures

Sources

"Jane's Pocket Book 9: Naval Armament" edited by Denis Archer
"Dutch Naval Weapons of the early 20th Century" by Stefan Boon (unpublished manuscript)
"The Naval Institute Guide to World Naval Weapon Systems 1991/92" by Norman Friedman
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Special help from Iwan Bos, Helen Peeters, Joakim Wohlfeil and Sjef Pijls

Page History

15 October 2007 - Benchmark
21 May 2023 - Converted to HTML 5 format, added additional ammunition and mounting information
11 August 2023 - Added Netherlands and Peruvian classes
28 May 2024 - Corrected class name of Columbian destroyers