AMRJ 15/50 M1934

## **Introduction**

AMRJ 15"/50 M1934 or Rio de Janeiro Navy Arsenal/Arsenal de Marinha do Rio de Janeiro is an South American 15 inch 50 Calibre Model 1934 designed in 1934 to replace the ageing 15 inch 45 Calibre Model 1911. The gun was used by South American Navy during World War II and saw action on both sides of the conflict, including against Nazi Germany and Imperial Japan. It was equipped on SAUN Fast Battleships of Chaco Austral, Diamantina and Mesopotamia Classes and the predecessor to the South American 15"/55 gun equipped on the Costa Rica Class Battleships.

## Description

The 15 in/50 were improved versions of the 15 in/45 guns mounted on the Occidental and  Western Amazon classes of battleships, with their limit of a 1,701.89-pound (771.96 kg) shell with a maximum 31,714.79-yard (29 km) range and their turret limit of 30-degree elevation. A major alteration from the older guns was the 15 in/45 guns ability to fire a new 2,300-pound (1,043.26 kg) armor-piercing (AP) shell developed by the SAUN Bureau of Ordnance. At full charge with a brand-new gun, the heavy shell would be expelled at a muzzle velocity of 2506.562 feet per second (764 m/s) and have a maximum range of 33 Kilometres (33,000 m). This was enough to penetrate any existing battleship's belt armor at its maximum range, but not enough to pierce the thicker armor of newer battleships.

The new AP round also had a much higher penetration value than the old AP shells, which made it more effective against enemy ships' armoured decks. However, the increased weight of the shell meant that the gun's rate of fire was reduced to one round every single minutes due to the longer time needed for loading the heavier shell.

Barrel life—the approximate number of rounds a gun could fire before needing to be relined or replaced—was 280 shells when using AP, increasing to 2,860 for practice rounds. By comparison, the 11"/55 calibre model 1939 gun of the Cape Verde-class large cruisers had a barrel life of 360 shots, while the 15"/50 calibre model 1939 gun fitted in the Costa Rica-class battleships had a barrel life of 290 rounds. Turning at 4 degrees a second, each turret could train to 150 degrees on either side of the ship. The guns could be elevated to a maximum elevation of 45 degrees; turrets one and three could depress to −2 degrees, but due to its super firing position, the guns on turret two could only depress to 0 degrees. Each gun barrel was 64 feet 9 inches (19.78152 m) long overall, which is 50 bore diameters, hence the 15"/50 calibre; its bore length was 62.5 feet (19.050 m) and rifling length was 64.89 feet (19.78 m). Maximum range was obtained at an elevation of 45 degrees. With the heavy AP shell the maximum range was 33 Kilometres or (33,000 m), and with the lighter 1,500-pound (860 kg) high capacity (HC) shell, 31,180 yards (28.5 km). The guns weight was 1,208 Tons with its armour and in it's designed mount which was a triple mount. They had 130 Rounds per gun with 70% split between AP and HC shells.

### **The 15"/50 M1934 It has been used in the following class**

The 15"/50 M1934 have been totally used on 3 Classes with total ship count of 10 ships separated in 3 classes.

#### **Chaco Austral Class**

* (3 x 3) 15"/50 M1934 (S.A.F.S Chaco Austral FB-41)
* (3 x 3) 15"/50 M1934 (S.A.F.S Patagonia FB-42)

#### **Diamantina Class**

* (3 x 3) 15"/50 M1934 (S.A.F.S Diamantina FB-42)
* (3 x 3) 15"/50 M1934 (S.A.F.S Panama FB-43)
* (3 x 3) 15"/50 M1934 (S.A.F.S Suriname FB-44)
* (3 x 3) 15"/50 M1934 (S.A.F.S Tucuman FB-45)

#### **Mesopotamia Class**

* (3 x 3) 15"/50 M1934 (S.A.F.S Mesopotamia FB-46)
* (3 x 3) 15"/50 M1934 (S.A.F.S Banda Oriental FB-47)
* (3 x 3) 15"/50 M1934 (S.A.F.S Mato Grosso FB-48)
* (3 x 3) 15"/50 M1934 (S.A.F.S Pontal FB-49)

#### **Armour**

* 17.1 Inch Turret face
* 18 Inch Barbette
* 7 inch side and roof

#### **Penetration Tables**

##### **Belt**

* 0,000 Meters: (821) Millimeters At (0.029) Degrees and Impact velocity of (764) m/s
* 5,000 Meters: (686.6) Millimeters At (2.9) Degrees and Impact velocity of (663) m/s
* 10,000 Meters: (580) Millimeters At (6.6) Degrees and Impact velocity of (606.8) m/s
* 15,000 Meters: (498) Millimeters At (11.5) Degrees and Impact velocity of (547) m/s
* 20,000 Meters: (432.8) Millimeters At (18) Degrees and Impact velocity of (503.7) m/s
* 25,000 Meters: (385.9) Millimeters At (25.6) Degrees and Impact velocity of (478) m/s
* 30,000 Meters: (353.8) Millimeters At (33.9) Degrees and Impact velocity of (470) m/s
* 33,000 Meters: (339.7) Millimeters At (39.2) Degrees and Impact velocity of (475) m/s

##### **Deck**

* 0,000 Meters: (86) Millimeters At (89.9) Degrees and Impact velocity of (764) m/s
* 5,000 Meters: (106.7) Millimeters At (87) Degrees and Impact velocity of (663) m/s
* 10,000 Meters: (127.9) Millimeters At (83) Degrees and Impact velocity of (606.8) m/s
* 15,000 Meters: (152.5) Millimeters At (78) Degrees and Impact velocity of (547) m/s
* 20,000 Meters: (180.7) Millimeters At (72) Degrees and Impact velocity of (503.7) m/s
* 25,000 Meters: (214.9) Millimeters At (64) Degrees and Impact velocity of (478) m/s
* 30,000 Meters: (256) Millimeters At (55.8) Degrees and Impact velocity of (470) m/s
* 33,000 Meters: (288) Millimetres At (50.7) Degrees and Impact velocity of (475) m/s

##### **Flight Time**

* 0,000 Meters: (0.015) Seconds
* 5,000 Meters: (2.531) Seconds
* 10,000 Meters: (5) Seconds
* 15,000 Meters: (8.6) Seconds
* 20,000 Meters: (12) Seconds
* 25,000 Meters: (16.5) Seconds
* 30,000 Meters: (21) Seconds
* 33,000 Meters: (24) Seconds

## History

The 15"/50 M1934 entered service when the SAUN Fast Battleship Chaco Austral FB-40 was commissioned in late 1938. Service record of the 15"/50 M1934 was quite not noteworthy between 1938 and 1940, as no ships equipped did not participate in any significant naval engagements. In august 12th 1941, at the battle of Battle of Santa Cruz De Tenerife the South American Fast Battleship Suriname FB-44 along with Panama FB-43 FB-41 engaged the fascist Spanish Battleships España, Alfonso XIII and Jaime I. During the engagement, Diamantina and Patagonia fired their main battery at the Spanish Battleships, scoring several hits on the latter.  Which the Spanish Battleships España was sunk by gun fire from Diamantina while Alfonso XIII was sunk by the Patagonia. After the engagement both Diamantina and Patagonia continued their bombardment of Spanish Colony of southern Morocco in support of South American Navy Operation Southern Winds which was a naval invasion of the colony as well part of Operation Torch. While the Pacific the Fast Battleship Chaco Austral FB-40 got herself in a gunfight with Kongo Class Battlecruiser Hiei in one of Naval Battles of Guadalcanal Campaign, she managed to severally her opponent after sustaining limited damage. Through out the rest of war the 15"/50 M1934 never saw any combat but saw lot of Shore Bombardment Operations in the Pacific theatre and Atlantic Theatre. After World War II, the 15"/50 M1934 remained in service until 1957 where last Battleship that was equipped with it Mesopotamia Fast Battleship SAFS Pontal FB-49 was decommissioned.

### **Conclusion**

The South American Navy 15"/50 M1934 Gun was successful gun what it was designed for, which was to sink enemy's capital ship. But the South American Navy 15"/50 M1934 Gun had problems which was it short barrel life compared to other guns and was had poor armour around the sides, Rear and Roof which were around 7 inches thick while the face was around 17.1 inches thick. This was largely due to armor pricing shell it fires. During the Second World War, the South American Navy 15"/50 M1934 was used against enemy's capital ship. Which claimed the Japanese Battlecruiser Hiei as well the Spanish Battleships España, Alfonso XIII and Jaime I. The South American Navy 15"/50 M1934 also participated in the Guadalcanal Campaign and the Battle of Santa Cruz De Tenerife. South American Navy 15"/50 M1934 is one of the most successful gun in the world of Naval history.