155 mm/50 model 1920 (155 mm)

Turrets A and B on Duguay-Trouin

Description

The 155 mm/50 model 1920 is a French naval gun. It served on French warships from 1920 till 1964 being retired from service with the decommissioning of the training cruiser Jeanne d'Arc.

Vehicles equipped with this weapon

• Duguay-Trouin
• Jeanne d'Arc
• Primauguet

General info

The gun features a notably slow rate of fire, particularly once the first stage ammunition is expended.

Available ammunition

The cannon comes with three distinct shell variants: standard HE shells that contain an large amount of explosive filler, SAP shells with relatively subpar penetration for its caliber, yet a sizable explosive filler, and base fuse shells (M1924 HE-BF) that possess the smallest filler of the three, yet have a good penetration capabilities against angled targets, making them a suitable complement to the SAP shells.

M1924 HE is a typical high explosive shell, featuring a relatively large explosive filler. It's best used against external components of the warships, such as the torpedo tubes or anti-aircraft batteries, and to start fires.

M1924 HE-BF, high explosive with base fuse, it can be used as a specialized armour-piercing shell, complimentary to the SAP. It's a type of shells very rarely found on cruisers (other notable gun featuring these shells being 6 inch/47 Mk.16 (152 mm) with its Mk.34 HC (base fuse) shells). Unlike regular HE, these shells will have to penetrate at least 7 mm of steel in order to deal damage, and then will explode only after 0.015s, which translates to nearly 13 meters. That is 4.26 meters deeper into the ship's hull than the SAP shells. That effectively means that shells can over-penetrate a number of destroyers (like Shimakaze with 11 m beam) and frigates (e.g. SKR-7 with 9.2 m beam) when hitting them perpendicularly across the hull, if it won't encounter any module inside of the ship. But a longer travel distance can be used to an advantage, when dealing with the unarmoured sections of a cruisers, such as the ammo racks on Kuma.

M1924 SAP is a shell dedicated specifically against an armoured targets. It will explode after penetrating at least 7 mm of steel, traveling up to 8.7 meters into the hull. SAP shell features much a higher penetration at a 0° AoA and over 25% larger explosive filler than the base fuse shells. But against an angled targets the base fuse shells offer a nearly identical penetration (1 to 3 mm difference across the range for 30 and 60° AoA) yet is far less likely to ricochet - while striking the target at 71°, the SAP shell has 100% ricochet chance, while the base fuse shell still has a 0% ricochet chance. These ricochet values are typical for the SAP shells across all nations.

Overall it makes SAP shells far more suitable when hitting the flat armour at a minimal angle, e.g. when shooting at the targets on parallel course, while the base fuse shells are better used against angled ships, e.g. when crossing the T.

Penetration statistics
Ammunition	Type of warhead	Penetration @ 0° Angle of Attack (mm)
		1,000 m	2,500 m	5,000 m	7,500 m	10,000 m	15,000 m
M1924 HE	HE	51	51	51	51	51	51
M1924 HE-BF	HE	87	78	64	53	45	34
M1924 SAP	SAPBC	142	126	104	87	73	55

Shell details
Ammunition	Type of warhead	Velocity (m/s)	Projectile mass (kg)	Fuse delay (s)	Fuse sensitivity (mm)	Explosive mass (TNT equivalent) (kg)	Ricochet
							0%	50%	100%
M1924 HE	HE	864	59	0	0.1	6.16	79°	80°	81°
M1924 HE-BF	HE	870	56.5	0.015	7	2.9	79°	80°	81°
M1924 SAP	SAPBC	870	56.5	0.01	7	3.67	48°	63°	71°

Comparison with analogues

The most apparent feature of this gun is its low sustained rate of fire. While its 17 ready-to-use shells are fired at a low, but acceptable 6 rounds per minute, the sustained fire rate of just 4 shells per minute is more typical for a battleship than a cruiser. The US 6 inch/47 Mk.16 features a 150% higher rate of fire.

This, to a degree, is offset by a large explosive filler of the shells. SAP shell with its 3,67 kg filler can output above-average 14,68 kg TNT equivalent per minute, nearly a double of 150 mm/45 SK L/45, yet significantly behind the 152 mm/57 B-38. HE shells on the other hand are below average, and the base fuse HE shells have some of the lowest TNT equivalent per minute for among the HE shells, but only below-average among the armour and semi-armour piercing shells.

It's also worth noting that the gun lacks any dedicated armour-piercing or anti-air shells. Making it tricky to use against bombers and impossible to penetrate effective armour in excess of 80 mm, which can be found on a number of ships in the BR range, notably even a slightly angled Svetlana-class or Kako.

HE

Cannon		Sample Ship	Ammo	Calibre (mm)	Muzzle velocity (m/s)	Sustained rate of fire (rounds/min)	Targeting speed (°/s)		TNT equivalent (kg)	TNT equivalent per minute (kg)	Penetration @ 0° Angle of Attack (mm)
							Horizontal	Vertical			5,000 m	10,000 m
	155 mm/50 model 1920	Duguay-Trouin	HE	155	864	4	6.4	6	6.16	24.64	51	51
	152/53 mm O.T.O. Mod.1929	RN Eugenio di Savoia	HE	152	935	8	6	5	2.39	19.12	29	29
	6 inch/47 Mk.16 (152 mm)	USS Helena	HE	152	812	10	4.2	8.5	5.88	58.8	49	49
	6 inch/53 Mk.12 (152 mm)	USS Trenton	HE	152	914	6	5.1	4.2	5.88	35.28	49	49
	150 mm/45 SK L/45	SMS Elbing	HE	150	835	7	4.2	4.2	1.6	11.2	21	21
	15 cm/48 KC/36	Z32	HE	150	835	7	8.5	6.8	3.91	27.37	37	37
	15 cm/60 SK C/25	Nürnberg	HE	150	960	12	6.8	5.1	3.91	46.92	37	37
	152 mm/57 B-38	Chapayev	HE	152	950	7.5	6.1	11	6	45	50	50
	6 inch/50 BL Mark XXIII (152 mm)	HMS Arethusa	HE	152	841	8	6	8.5	3.96	31.68	37	37
	15 cm/50 Type 41	IJN Agano	HE	152	850	6.2	10	6	3.17	19.65	35	35

SAP / AP

Note that the HE-BF shell is located in this table due to its penetration and filler characteristics.

Cannon		Sample Ship	Ammo	Calibre (mm)	Muzzle velocity (m/s)	Sustained rate of fire (rounds/min)	Targeting speed (°/s)		TNT equivalent (kg)	TNT equivalent per minute (kg)	Penetration @ 0° Angle of Attack (mm)
							Horizontal	Vertical			5,000 m	10,000 m
	155 mm/50 model 1920	Duguay-Trouin	SAPBC	155	870	4	6.4	6	3.67	14.68	80	61
	155 mm/50 model 1920	Duguay-Trouin	HE-BF	155	870	4	6.4	6	2.9	11.6	69	53
	152/53 mm O.T.O. Mod.1929	RN Eugenio di Savoia	APHEBC	152	900	8	6	5	0.8	6.4	168	95
	6 inch/47 Mk.16 (152 mm)	USS Helena	APCBC	152	762	10	4.2	8.5	0.9	9	182	120
	6 inch/53 Mk.12 (152 mm)	USS Trenton	SP Common	152	914	6	5.1	4.2	0.977	5.86	138	85
	150 mm/45 SK L/45	SMS Elbing	SAPBC	150	835	7	4.2	4.2	1.05	7.35	61	37
	150 mm/45 SK L/45	SMS Elbing	APCBC	150	835	7	4.2	4.2	0.99	6.93	153	93
	15 cm/48 KC/36	Z32	SAPBC	150	835	7	8.5	6.8	3.32	23.24	74	45
	15 cm/48 KC/36	Z32	APCBC	150	835	7	8.5	6.8	1.32	9.24	147	90
	15 cm/60 SK C/25	Nürnberg	SAPBC	150	835	12	6.8	5.1	3.32	39.84	74	45
	15 cm/60 SK C/25	Nürnberg	APCBC	150	960	12	6.8	5.1	1.32	15.84	182	109
	152 mm/57 B-38	Chapayev	SAPBC	152	950	7.5	6.1	11	5.9	44.25	117	74
	152 mm/57 B-38	Chapayev	APCBC	152	950	7.5	6.1	11	1.69	12.68	226	143
	6 inch/50 BL Mark XXIII (152 mm)	HMS Arethusa	SAPBC	152	841	8	6	8.5	1.7	13.6	137	90
	15 cm/50 Type 41	IJN Agano	SAP	152	850	6.2	10	6	2.92	18.1	52	34

Usage in battles

The 155 mm/50 model 1920 is perfectly capable of dealing with a majority of the targets it will encounter in its BR range. It has a respectable damage output and is more than capable of ammo-racking any destroyer or early light cruiser. The low muzzle velocity makes it tricky to hit manoeuvring targets at distance, but it also makes it easier to hit the targets behind a hard cover, or dive shells into the ammo racks at longer ranges. Where it struggles are armoured targets, especially heavy cruisers at range if they do not have unarmoured ammo racks. This makes vessels like Prinz Eugen (BR 5.7) extremely difficult to counter without the help of other ships.

Pros and cons

Pros:

• Large explosive fillers
• Good horizontal targeting speed

Cons:

• Low muzzle velocity
• No dedicated armour-piercing shells
• No anti-air shells, be it time or variable fuse

History

The canon de 155 mm Modèle 1920 was a post-WW1 design with the primary aim to counter a lighter warships.

The guns used loading mechanism derived from the French battleships. Two hoists provided shells and propellant to the work room below the turret itself, which were then transferred directly into the turret right next to the gun breeches, where they were transferred to loading trays and rammed into the breech. While loading mechanism was largely electrically powered, it still failed to achieve a higher rate of fire than the 203 mm guns of the era.

The turrets themselves were the world's first to have a fully electrically powered training angle and elevation.

Seeking an increased rate of fire, the French replaced 155 mm with the Canon de 152 mm Modèle 1930 for the later designs.

Media

Excellent additions to the article would be video guides, screenshots from the game, and photos.

See also

Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:

• reference to the article about the variant of the cannon/machine gun;
• references to approximate analogues by other nations and research trees.

External links

• [Wikipedia] Canon de 155 mm Modèle 1920
• [NavWeaps] 155 mm/50 (6.1") Model 1920
• [Clausuchronia] Canon de 155 modèle 1921
• Jordan John and Jean Moulin. 2013. French Cruisers 1922-1956. Annapolis Maryland: Naval Institute Press.

France naval cannons
37 mm	37 mm/50 model 1925 · 37 mm/50 model 1933
47 mm	3 pdr QF Hotchkiss
57 mm	57 mm/60 ACAD Mle 1951
75 mm	75 mm/50 Canet model 1891 · 75 mm/50 model 1922
90 mm	90 mm/50 model 1926
130 mm	130 mm/40 model 1919
138.6 mm	138.6 mm/55 model 1910 · 138.6 mm/40 model 1927 · 138.6 mm/50 model 1929 · 138.6 mm/50 model 1934 R1938
152 mm	152 mm/55 model 1930
155 mm	155 mm/50 model 1920
203 mm	203 mm/50 model 1924
305 mm	305 mm/45 model 1906-10
340 mm	340 mm/45 model 1912
	Foreign:
20 mm	2 cm/65 C/38 (Germany) · 2 cm/65 Flakvierling 38 (Germany) · 20 mm/70 Oerlikon Mk.II (USA/Britain)
40 mm	2pdr QF Mk.IIc (Britain) · 2pdr QF Mk.VIII (Britain) · Bofors L/60 Mark 2 (USA) · Bofors L/60 Mark 3 (USA)
87.6 mm	Ordnance QF 25pdr (87.6 mm) (Britain)
102 mm	4 in QF Mark V (Britain) · 4 inch/45 Mark XVI (Britain)
105 mm	SK C/33 AA (Germany)
128 mm	12.8 cm/45 SK C/34 (Germany)
150 mm	15 cm/48 KC/36 (Germany)