The 3-inch anti-aircraft gun M3 was an

anti-aircraft gun Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...

which served throughout the 1930s and possibly into early World War II. Developed from the earlier 3-inch M1917 and 3-inch M1918 guns, it was in the process of being replaced by the time of the US entry into

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 ...

, but was subsequently adapted into an

anti-tank gun An anti-tank gun is a form of artillery designed to destroy tanks and other armored fighting vehicles, normally from a static defensive position. The development of specialized anti-tank munitions and anti-tank guns was prompted by the appearance ...

role, both free-standing (as the 3-inch M5) and in a self-propelled

tank destroyer A tank destroyer, tank hunter, tank killer, or self-propelled anti-tank gun is a type of armoured fighting vehicle, armed with a direct fire artillery gun or missile launcher, designed specifically to engage and destroy enemy tanks, often wi ...

(the M10). It may have seen action in the Pacific Theatre.

History

During the late 1920s, M1917 and M1918 guns were fitted with removable barrel liners and re-designated as 3-inch M1, M2, or M3 guns, depending on the variant they were upgraded from. The most numerous variant was the M3 which was introduced in 1928 and consisted of a new barrel with a removable autofretted liner. During the 1930s further upgrades were proposed but these were abandoned with the adoption of the 90 mm gun M1 in 1938.

Design

The M3 consisted of a barrel 50 calibers in length, which had a removable liner and a semi-automatic vertical sliding-wedge breech. The barrel had a hydro-pneumatic recoil system and when fired the breech ejected the shell casing and remained open until a new round was loaded. The M2A2

cruciform Cruciform is a term for physical manifestations resembling a common cross or Christian cross. The label can be extended to architectural shapes, biology, art, and design. Cruciform architectural plan Christian churches are commonly described ...

carriage had a circular center section and four perforated steel

outriggers An outrigger is a projecting structure on a boat, with specific meaning depending on types of vessel. Outriggers may also refer to legs on a wheeled vehicle that are folded out when it needs stabilization, for example on a crane that lifts ...

for stability. For transport, the outriggers folded and a two-wheeled, single axle bogie could be screwed onto the outriggers at each end. The carriage had pneumatic tires, electric brakes and was capable of being towed at high speeds. The gun was provided with a set of equilibrators and was capable of both high angle fire +80° and 360° of traverse.

Anti-tank gun

In September 1940 a project started to adapt the 3-inch gun to the

anti-tank Anti-tank warfare originated from the need to develop technology and tactics to destroy tanks during World War I. Since the Triple Entente deployed the first tanks in 1916, the German Empire developed the first anti-tank weapons. The first deve ...

role, starting with the T9 experimental model but equipping it with the breech, recoil system and carriage borrowed from the 105mm M2 howitzer. The gun was accepted for service as the 3-inch M5. A similar derivative of the T9 – the 3-inch M6 – was intended to be mounted on the M5 self-propelled gun, which was eventually abandoned. A final adaptation was the 3-inch M7, which included minor modifications for mounting on the

M6 heavy tank The Heavy Tank M6 was an American heavy tank designed during World War II. The tank was produced in small numbers and never saw combat. Development Because of limited budgets for tank development in the interwar years, at the outbreak of Worl ...

and

M10 tank destroyer The M10 tank destroyer was an American tank destroyer of World War II. After US entry into World War II and the formation of the Tank Destroyer Force, a suitable vehicle was needed to equip the new battalions. By November 1941, the Army requeste ...

. The M7 saw wide use although it was supplanted to some extent by more powerful weapons such as the 90mm M3 and the British

QF 17 pounder The Ordnance Quick-Firing 17-pounder (or just 17-pdr)Under the British standard ordnance weights and measurements the gun's approximate projectile weight is used to denote different guns of the same calibre. Hence this was a 3-inch gun, of which ...

. A total of 6,824 M7 guns were manufactured.

Ammunition

The M3 fired a Fixed QF 76.2 × 585R round and a number of different styles of ammunition were available: *

Armor-piercing Armour-piercing ammunition (AP) is a type of projectile designed to penetrate either body armour or vehicle armour. From the 1860s to 1950s, a major application of armour-piercing projectiles was to defeat the thick armour carried on many warsh ...

* Armor-piercing capped *

High explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

Photo gallery

File:3inchUSM1918AAGunAutoTrailerTravelingPosition.jpg, The predecessor of the M3; the M1918 in traveling position. File:SC180758t.jpg, No. 2 Gun Crew, Btry D, 208th CA AA, man their 3-inch AA gun at New Fighter Strip, Dobodura, New Guinea (17 May 1943). File:Secretary of War inspects latest mobile anti-aircraft unit 35383v.jpg, Secretary of War James W. Good inspects an M3 in traveling position near the White House in 1929. File:3-inch_Gun_M6.jpg, 3-inch anti-tank gun M6 at Fort Lewis, Washington, USA. Image:M10 1943.jpg, M10 tank destroyer with the 3-inch gun M7.

References

External links

* {{DEFAULTSORT:3-inch anti-aircraft gun M3 76 mm artillery Anti-aircraft guns of the United States World War II anti-aircraft guns World War II artillery of the United States Military equipment introduced in the 1920s