A new design used on France's Treaty Cruisers in twin turrets. Also used 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.
|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.
|Projectile Types and Weights 1||APC M1927: 271.4 lbs. (123.1 kg)
APC M19??: 262.5 lbs. (119.07 kg)
APC M1936 2: 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)
|Projectile Length||APC M1936: 38.2 in (97 cm)
Others: 39.6 in (100.5 cm)
|Propellant Charge 3||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
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.
|Weight 4||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.
- ^The 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.
- ^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" list 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)
- "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
- 22 July 2007
- 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.