The 4.5 inch gun M1 was a

field gun A field gun is a field artillery piece. Originally the term referred to smaller guns that could accompany a field army on the march, that when in combat could be moved about the battlefield in response to changing circumstances ( field artille ...

developed in the United States in the beginning of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. It shared the same carriage with the 155mm Howitzer M1 and fired the same ammunition as the British BL 4.5 inch Medium Field Gun. Beginning in 1944, the weapon was used by the

U.S. Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cl ...

corps Corps (; plural ''corps'' ; from French , from the Latin "body") is a term used for several different kinds of organization. A military innovation by Napoleon I, the formation was first named as such in 1805. The size of a corps varies great ...

-level artillery; with the end of hostilities, it was declared obsolete.

Development and production

In 1920 the US Army Ordnance Department started to work on a new medium field gun. Since the

US Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

had already employed the

4.7-inch gun M1906 The 4.7-inch gun M1906 (initially the M1904) was designed and issued by the United States Army Ordnance Department beginning in 1906, with the first units receiving the weapon in 1911.Williford, pages 70-71 It was of the field gun type. It was ...

prior to

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, and during the war in limited numbers, this caliber was also selected for the new weapon. The development resulted in the 4.7-inch Gun M1922E on Carriage M1921E. Because of lack of funding, the design never reached production.Hogg – ''Allied Artillery of World War II'', p 50-51.Zaloga – ''US Field Artillery of World War II'', p 18-19. In 1939 the program was restarted; the renewed design, designated the 4.7-inch gun T3, was ready by early 1940. It utilized the same carriage as the concurrently developed 155 mm howitzer. At this stage, the Army decided to change the caliber of the weapon to use British 4.5-inch ammunition. The modified gun was standardized in April 1941 as the 4.5-inch Gun M1 on Carriage M1. Production started in September 1942 and continued until February 1944.

Variants

47inch-gun-155mm-howitzer-carriage-M1920-FAJ19220101-1.jpg, 4.7-inch Gun M1920 on Carriage M1920 in battery 47inch-gun-155mm-howitzer-carriage-M1920-FAJ19220101-2.jpg, 155 mm howitzer on the same carriage from the front 47inch-gun-155mm-howitzer-carriage-M1920-FAJ19220101-4.jpg, The 4.7-inch gun in travelling position 47inch-gun-carriage-M1921E-FAJ19220101-1.jpg, 4.7" Gun M1922E on Carriage M1921E in travelling position 47inch-gun-carriage-M1921E-FAJ19220101-2.jpg, The same gun in firing position * 4.7 inch Gun M1920 on Carriage M1920 with 65-degree maximal elevation (the carriage was also designed to be used with 155-mm howitzer) weighing . * 4.7 inch Gun M1922E on Carriage M1921E of a similar design and same ballistics, but with 45-degree maximal elevation and lighter, just . * 4.7 inch Gun T3 (1940). * 4.5 inch Gun M1 on Carriage M1 (1941). The weapon was experimentally mounted on a lengthened chassis of the

M5 light tank The M3 Stuart/Light Tank M3, was an American light tank of World War II. An improved version of the tank entered service as the M5 in 1942 to be supplied to British and other Commonwealth forces under lend-lease prior to the entry of the U.S. in ...

, in mount M1. The resulting vehicle received the designation 4.5in Gun Motor Carriage T16. A single prototype was built.Hunnicutt – ''Stuart: A History of the American Light Tank'', p 337-338.

Description

The M1 was very similar in construction and appearance to the 155mm Howitzer M1. The only significant difference was its

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of 4.5 inch (114 mm) caliber. The tube had uniform right hand twist, with one turn in 32 calibers.Hunnicutt – ''Stuart: A History of the American Light Tank'', p 506. The unbalanced weight of the barrel was supported by two equilibrator springs. The breach was of

interrupted screw Breech from Russian 122 mm M1910 howitzer, modified and combined with 105 mm H37 howitzer barrel An interrupted screw or interrupted thread is a mechanical device typically used in the breech of artillery guns. It is believed to have be ...

type; the recoil system hydro-pneumatic, variable length. The carriage was of

split trail A gun carriage is a frame and mount that supports the gun barrel of an artillery piece, allowing it to be maneuvered and fired. These platforms often had wheels so that the artillery pieces could be moved more easily. Gun carriages are also use ...

type, unsprung and had wheels with pneumatic tires. In firing position, the weapon was supported by a retractable pedestal. The gun was equipped with M12 panoramic sight.''Technical Manual TM 9-2005 volume 3, Infantry and Cavalry Accompanying Weapons'', p 59-62.

Service

The M1 equipped 16 field artillery battalions in

Northwest Europe Northwestern Europe, or Northwest Europe, is a loosely defined subregion of Europe, overlapping Northern and Western Europe. The region can be defined both geographically and ethnographically. Geographic definitions Geographically, Northw ...

; the 172nd, 176th, 199th, 211th, 259th, 770th through 775th, 777th, 935th, 939th, 941st, and 959th. It was employed for

support. M5 High Speed Tractors was assigned as prime movers. The weapon was declared obsolete in September 1945. The gun had good range, longer than the World War I-era 155 mm Gun M1918MI, and nearly five kilometers longer than its 155 mm howitzer sibling. It was out-ranged by the newer 155 mm Gun M1, but this weapon was nearly three times heavier. On the other hand, the 4.5-inch gun was criticized for the insufficient power of its

high-explosive shell A shell, in a military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military context. Modern usage ...

. The shell was produced from low grade ("19 ton") steel, which necessitated thick walls. As a result, it carried only about two kilograms of

TNT Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...

or substitute, less than the 105 mm high-explosive shell. Additionally, it was felt that having a small number of guns of an atypical caliber unnecessarily complicated logistics.

Ammunition

The M1 utilized separate loading, bagged charge ammunition. Only high explosive projectile was available.''Technical Manual TM 9-1904, Ammunition Inspection Guide'', p 486-490. The projectile could be fired with propelling charge M7 (normal) at reduced velocity or with propelling charge M8 (super) to achieve full velocity. The dummy propelling charge M6 simulated the M8 charge.''Technical Manual TM 9-1901, Artillery Ammunition'', p 300-304. The velocity and range data in the table below is for the M8 charge. : : : :

Notes

References

* * * * * * * * * {{Use dmy dates, date=June 2017 World War II artillery of the United States World War II field artillery 114 mm artillery Weapons and ammunition introduced in 1942