12 cm/50 (4.7") Model 1950
Updated 14 October 2007

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 breechblock has closed.

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.


12 cm on Netherlands Tromp Class Frigate


12 cm mounting on RSN Halland


Forward 12 cm mounting on RSN Halland


HNLMS Amsterdam arriving at Willemstad, Curacao in 1977
Photograph courtesy of Sjef Pijls, who was her deputy weapon engineering officer in 1977

Gun Characteristics
Designation Sweden:  12 cm/50 (4.7") Model 1950
Netherlands:  120 mm Mark 10
Ship Class Used On Netherlands Tromp Class
Swedish Halland Class
Colombian Siete de Julio Class
Date Of Design 1944 - 1950
Date In Service 1950
Gun Weight N/A
Gun Length N/A
Bore Length about 236.2 in (6.000 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire 42 - 45 rounds per minute
(42 gives the optimum dispersion)
Powder Charge N/A
Type Fixed
Weight of complete round HE - 88.2 lbs. (40 kg)
Projectile Types and Weights HE - 52 lbs. (23.5 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge N/A
Muzzle Velocity 2,707 fps (825 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
Elevation With 52 lbs. (23.5 kg) HE Shell
Range @ 45 degrees 20,890 yards (19,100 m)
AA Ceiling about 9,800 feet (9,000 m)
Mount / Turret Data
Designation Twin Turrets
   Tromp (2) and Halland (2)
Weight  114,600 lbs. (52,000 kg)
Elevation -10 / +85 degrees
Elevation Rate 40 degrees per second
Train about +150 / -150 degrees
Train Rate 25 degrees per second
Gun recoil N/A
Note:  The mountings originally weighed about 143,300 lbs. (65,000 kg).  This was reduced to the above figure by removing the emergency diesel engine, the fuze setting mechanisms and the local fire control equipment.
Data from
"Jane's Pocket Book 9:  Naval Armament" edited by Denis Archer
"The Naval Institute Guide to World Naval Weapon Systems 1991/92" by Norman Friedman
Special help from Iwan Bos, Joakim Wohlfeil and Sjef Pijls