A new design used on France's Treaty Cruisers in twin turrets and in a special lightweight twin mounting on the submarine Surcouf.

This weapon was of simple construction with a thick autofretted A tube, shrunk jacket and breech ring. The Welin breech-block opened upwards.

Actual bore diameter was 20.30 cm (7.992").

A note on sources: Many references state that Algérie used a longer 55 caliber gun, but recent research by John Jordan and Jean Moulin in their "French Cruisers: 1922 - 1956" has determined that she carried the same 50 caliber guns as did the older cruisers.

Gun Characteristics

Designation 203 mm/50 (8") Model 1924
Ship Class Used On Duquesne, Suffren, Surcouf and Algérie classes
Date Of Design 1924
Date In Service 1928
Gun Weight 20.389 tons (20.716 mt) including BM
Gun Length oa 413.4 in (10.5 m)
Bore Length 399.6 in (10.150 m)
Rifling Length 319.8 in (8.122 m)
Grooves (60) 0.75 in deep x 0.295 in (1.9 mm x 7.5 mm)
Lands 0.118 in (3.0 mm)
Twist Uniform RH 1 in 25.59
Chamber Volume 5,595 in3 (91.682 dm3)
Rate Of Fire Cruisers: 4 - 5 rounds per minute 1
Surcouf: 3 rounds per minute
  • ^Planned rate of fire for cruisers was 5 - 6 rounds per minute, but in practice it was closer to the above values.


Type Bag
Projectile Types and Weights 1a APC M1927: 271.4 lbs. (123.1 kg)

APC M19??: 262.5 lbs. (119.07 kg)

APC M1936 2a: 295 lbs. (134 kg)
HE M1927: 273.0 lbs. (123.82 kg)
HE M19??: 263.9 lbs. (119.72 kg)
Bursting Charge APC M1927: 17.8 lbs. (8.07 kg) Mélinite
HE: about 18.2 lbs. (8.3 kg)
Others: N/A
Projectile Length APC M1936: 38.2 in (97 cm)
Others: 39.6 in (100.5 cm)
Propellant Charge 3a For APC M1936: 103.6 lbs. (47 kg) BM 13
Others: 116.8 lbs. (53 kg)
Muzzle Velocity APC M1936: 2,690 fps (820 mps)
Others: 2,789 fps (850 mps)
Working Pressure APC M1936: about 19.0 tons/in2 (3,000 kg/cm2)
APC: 20.3 tons/in2 (3,200 kg/cm2)
Approximate Barrel Life about 600 rounds
Ammunition stowage per gun Surcouf: 300 rounds
Others: N/A
  • ^
    Actual French designations
    APC M1927 Opf Mle 1927
    APC M19?? Opf Mle 19??
    APC M1936 Opf Mle 1936
    HE M1927 OEA Mle 1927
    HE M19?? OEA Mle 19??
  • ^

    APC M1936 added a dye bag in 1939. Colors were assigned as follows:

    Class Colour
    Duquesne red
    Tourville yellow
    Suffren green
    Others N/A
  • ^The propellant charge was in halves.


Elevation APC M1927 APC M1936 HE M1927
30 degrees 30,620 yards (28,000 m) --- ---
45 degrees 34,340 yards (31,400 m) about 32,800 yards (30,000 m) about 32,800 yards (30,000 m)

Mount/Turret Data

Designation 1b Cruiser Two-gun Turret 2b
   Duquesne (4) and Suffren (4): Model 1924 3b
   Algérie (4): Model 1931

Cruiser Three-gun Turret 2b
   C5 and St. Louis (3): N/A

Submarine Twin Mounting
   Surcouf (1): Model 1929 4b

Weight 5b Model 1924: 177 tons (180 mt)
Model 1931: about 220 tons (240 mt)
Model 1929: N/A
Elevation Model 1924 and Model 1931: -5 / +45 degrees
Model 1929: -5 / +30 degrees
Elevation Rate Model 1924: about 10 degrees per second
Model 1929: N/A
Train Model 1924 and Model 1929: about +90 / -90 degrees
Train Rate Model 1924 and Model 1931: 6 degrees per second
Model 1929: N/A
Gun recoil 27.5 in (70 cm)
Loading Angle -5 / +10 degrees
  • ^In 1939 the French started designing new cruisers that were intended to replace the Duguay-Trouin class. The preliminary design was known as "C5" and was for a 10,000 ton Treaty Cruiser similar to Algérie but having nine 203 mm (8") guns in three turrets. The start of the war ended all treaty restrictions and in early 1940 a more ambitious nine-gun design known as "St. Louis" was under consideration. Little more than some preliminary sketches for a ship of around 15,000 tons were completed before the June 1940 Armistice halted all work.
  • ^2.12.2The cruiser mountings used catapult rammers cocked by the recoil forces to load projectiles while propellant charges were loaded by hand. Guns were individually sleeved. Each gun used a 30 hp elevating electric motor and the guns could be coupled together. Turrets used a 22.5 hp electric training motor with hydraulic drive and were equipped for RPC for training during the mid-1930s refits. However, RPC for elevation was not added. Shell rooms were generally below the magazines, except for some bow mountings which were on the same level. Dredger hoists from the magazines ran up to a working chamber where ammunition was transferred to the upper cage hoists which each carried a projectile and two half charges. Upper hoists ended on the outside of the guns and the projectiles were transferred by swinging arms which were locked to the guns for loading.
  • ^Model 1924 gun axes were 74 in (188 cm) apart while those in Model 1929 were about 104 in (264 cm) apart.
  • ^The Model 1929 used on the submarine Surcouf could open fire within 2.5 minutes after she surfaced. Guns were not individually sleeved and the turret was water-tight.
  • ^

    The weight differences for the cruiser turrets were mainly due to armor thickness, which "French Cruisers: 1922 - 1956" lists as follows:

    Model 1924 - Duquesne and Suffren classes
    Front 1.2 in (3 cm)
    Sides 1.2 in (3 cm)
    Roof 1.2 in (3 cm)
    Rear 1.2 in (3 cm)

    This protection was provided by riveting two 0.6 in (1.5 cm) HT plates together.

    Model 1931 - Algérie
    Front 3.9 in (10 cm)
    Sides 2.8 in (7 cm)
    Roof 2.8 in (7 cm)
    Rear 1.96 - 3.3 in (5 - 8.5 cm)
    Floor 1.6 in (4 cm)

Additional Pictures


"Warship Volume VII" article by Francis J. Allen
"Naval Weapons of World War Two" by John Campbell
"French Cruisers: 1922 - 1956" by John Jordan and Jean Moulin
"Navies of the Second World War - The French Navy" by Henri le Masson
"Cruisers of World War Two" by M.J. Whitley
Ministère de la défense

Page History

22 July 2007 - Benchmark
03 March 2012 - Updated to latest template
28 March 2013 - Added photographs of Foch and Algérie
06 April 2013 - Added projectile and mounting information, notes on Algérie and note on 1939-1940 designs
08 January 2016 - Corrected training angles for Surcouf. Redid side view photograph of Surcouf and added new photograph of Surcouf showing the turret training.
11 November 2020 - Updated to HTML 5 format