37 mm gun M3

The 37 mm gun M3 is the first dedicated

Like many other light anti-tank guns, the M3 was widely used in the infantry support role and as an anti-personnel weapon, firing high-explosive and canister rounds.

The M5 and M6 tank mounted variants were used in several models of armored vehicles most notably in the Stuart

Development and testing continued until late 1938. Several variants of gun and carriage were proposed until on 15 December a combination of the T10 gun and T5 carriage was officially adopted as the 37 mm gun M3 and carriage M4.[1] Although the weapon followed the concept of the PaK 36 and was often referred to as a copy of it,^[3] the M3 differed significantly from the German design and used different ammunition.

The gun was manufactured by Watervliet Arsenal and the carriage by Rock Island Arsenal. The first production examples of the M3 were delivered in July 1940. It took until August 1941 for production to accelerate, and some infantry antitank units were forced to use wooden mock-ups of the new gun or their original weapons (37 mm gun M1916) during the Louisiana Maneuvers and Carolina Maneuvers, and did not get their first weapons until late 1941. Production continued until October 1943.^[4][1][5]

Minor changes in the gun construction were introduced during production. The carriage received a modified shoulder guard and traverse controls (carriage M4A1, standardized on 29 January 1942). Although ordnance requested an upgrade of all M4 carriages to M4A1, this process was not completed.

In an attempt to increase the armor penetration of the M3, several squeeze bore adapters (including the British Littlejohn adaptor) were tested; none was adopted. Experiments with rocket launchers on the M4 carriage (e.g. 4.5 in (110 mm) rocket projector T3) did not produce anything practical either.^[1]

Description

The barrel was of one-piece forged construction, with uniform rifling (12 grooves, right-hand twist, one turn in 25 calibers). The breech end of the barrel was screwed into a breech ring. The breech mechanism was of standard vertical sliding-block type, but unlike the overwhelming majority of the anti-tank guns of the era, it was not semi-automatic, meaning that a crew member had to manually open and close the breech at each shot. The barrel was fitted with a hydrospring recoil system.^[9]

The carriage was of split trail type, with pneumatic tires but without any spring suspension whatsoever.^[9] Mounted on the axle next to the wheels were the "wheel segments"; these were segment-shaped supports that could be lowered to provide more stability in the firing position or raised so that they would not impede movement of the gun.

The telescopic sight on the M6 and both elevation and traverse controls were located on the left side, so one gunner was able to aim the gun. The traverse gear had a release mechanism which allowed free movement of the barrel in case a quick traverse was needed.^[9]

Organization

US Army

Under the April 1942 organization, each infantry

Finally, U.S. armored divisions under the March 1942 organization possessed 68 37 mm anti-tank guns. Of these, 37 belonged to the armored infantry regiment (four in each company and one in regiment HQ); 27 to the armored engineer battalion; three to the divisional train and one to division HQ.[14]

US Marine Corps

Under the D-series Tables of Organization (TO) from 1 July 1942, the role of AT weapons in Marine Corps service was officially entrusted to 20 mm automatic guns, which were in the regimental weapon company (three platoons) and the battalion weapon company (one platoon). In practice, units used the World War I-era 37 mm M1916 for training. They were equipped with the M3 (four in each platoon) before being sent to the frontline. Additionally, a divisional special weapons battalion was equipped with self-propelled 37 mm GMC M6.^[15]

Under the E-series TO from 15 April 1943, self-propelled guns in the divisional special weapons battalion were replaced with eighteen 37 mm towed guns in three batteries of six; an infantry regiment had a weapons company with 12, in three platoons of four. The battalion-level AT guns were removed. In total, a division possessed 54 pieces. The F-series TO from 5 May 1944 removed the special weapons battalion from the divisional organization, resulting in a total of 36 guns per division. The subsequent G-series TO reduced regimental weapon companies to two platoons, meaning 24 pieces per division. Although the G-series TO was only adopted on 4 September 1945, in practice in some divisions this change was introduced early in 1945.^[16]

Other operators

The only major

The M3 saw action for the first time during the

The 37mm gun was used as the primary armament for M3/M5 Stuart light tanks and M8 Greyhound armored cars. AP rounds from these guns could defeat light enemy armor, including all Japanese and Italian armor, German half-tracks and armored cars, and most surfaces of tanks and early self-propelled guns based on the German Panzer II, Panzer III, and early Panzer IV chassis, but were useless against later Panzer IV, Panzer VI (Tiger) tanks and the frontal armor of Panzer V (Panther) tanks. It was also similarly useless against later, more heavily armored self-propelled guns and Jagdpanzer tank destroyers. The HE rounds were not powerful enough for effective infantry support in most situations. The rounds were enough, however, to attack enemy light reconnaissance units, and both the M3/M5 Stuart and M8 Greyhound were restricted to reconnaissance for the majority of the war in Europe. Canister rounds were often used to good effect against Japanese infantry in many battles, such as Bloody Ridge.^{[citation needed]}

There were also serious issues with the gun's ability to function effectively in the infantry support role.

The M3 was phased out of U.S. service soon after the end of the war.[8]

Variants

• Test variants:
  • T3 – the first prototype.^[1]
  • T7 – a prototype with semi-automatic horizontal sliding-block breech.^[2]
  • T8 – a prototype with Nordenfelt eccentric screw breech.^[2]
  • T10 – standardized as M3 (1938) – an adopted version, with manual vertical block breech.^[1][2]
• Model variants
  • M3 towed version, manual breech.
    • M3A1 (1942) – version with threaded barrel end to accept a muzzle brake, which was never issued.^[1]
  • M5 (1939) – tank mounted variant with shorter barrel.^[29]
  • M6 (1940) – tank mounted variant with barrel of the original length and with semi-automatic breech.^[29]
• Carriage variants:
  • T1, T1E1 – prototypes.^[1]
  • T5, standardized as M4 – first adopted version.^[1]
  • M4A1 (1942) – carriage with improved traverse controls.^[1]
  • In 1942, the Airborne Command requested a version with removable trails. A prototype was tested, but in 1943 the project was dropped as unnecessary.^[1]

At least in one case,

Two tank gun variants were developed based on the barrel of the M3. The first, initially designated M3A1 but renamed M5 on 13 October 1939, was shortened by 5.1 in (130 mm) to avoid damage to the tube in wooded areas. Later, a variant with a semi-automatic breech (with empty cartridge ejection) was developed. This variant—initially designated M5E1, adopted as M6 on 14 November 1940—received a full length barrel. The tubes were interchangeable, but replacing M5 with M6 and vice versa would result in an unbalanced mount and was therefore prohibited.^[29] These guns were mounted on several models of tanks and other armored vehicles:

• Light Tank M2A4: M5 in mount M20. The recoil mechanism, protruding beyond the gun mask, had to be protected by an armored casing.^[32]
• Light Tank M3: M5 in mount M22, in late production vehicles M6 in mount M23. These mounts were fitted with more compact recoil mechanism, eliminating the need for the protective casing.^[33]
• Light Tank M3A1, M5: M6 in mount M23.^[34]
• Light Tank M3A3, M5A1: M6 in mount M44.^[34]
• Light Tank (Airborne) M22: M6 in mount M53.^[35]
• M3 series medium tanks (as a secondary weapon): M5 or M6 in mount M24.^[36]
• Heavy Tank M6 (as a secondary weapon): M6 in mount T49.^[37]
• LVT(A)-1 "amtank": M6 in mount M44.^[34]
• 37 mm Gun Motor Carriage T22 – eventually Light Armored Car M8: M6 in mount M23A1; the competing designs 37 mm Gun Motor Carriage T43 / Light Armored Car T21 and 37 mm Gun Motor Carriage T23 / Light Armored Car T23 mounted the same weapon.^[38]
• Armored Car T13.^[39]
• Armored Car T17: M6 in mount M24.^[40]
• Armored Car T17E1 in the "Staghound Mk I" configuration: M6 in mount M24A1.^[41]
• The first pilot of the Armored Car T18: M6. The production variant T18E2 received the 57mm M1.^[42]
• Armored Car T19: M6 in mount M23A1.^[43]
• Armored Car T27: M6 in mount M23A1 modified.^[44]
• Armored Car T28 / M38: M6 in mount M23A2.^[45]
• British Humber Armoured Car Mk IV: M6.^[46]

Versions of the gun in turret mounts were also used in the

• 37 mm Gun Motor Carriage T2 (Bantam jeep).^[50]
• 37 mm Gun Motor Carriage T8 (Ford 4x4 "Swamp Buggy").^[51]
• 37 mm Gun Motor Carriage T13, T14 (Willys 6x6 "Super Jeep").^[52]
• 37 mm Gun Motor Carriage T21 / M4 / M6 (Fargo 3/4 ton 4x4 truck).^[53]
• 37 mm Gun Motor Carriage T33 (Ford 3/4 ton 4x4 cargo carrier).[54]
• M3A1E3 Scout Car.^[55]
• The gun was sometimes mounted on
  M2 Halftrack,^[56] M29 Weasel^[8] and on the 1/4 ton Willys MB / Ford GPW jeep
  (see photo on the right).

The M3 utilized fixed ammunition. Projectiles were fitted with a 37x223R cartridge case, designated Cartridge Case M16. Available projectiles included armor-piercing, high-explosive and canister. 1943 Soviet analysis described armor-piercing shots as modern, but criticized the M63 HE shell, claiming its M58 base fuze didn't work properly in tests.[58]

Armor penetration of the M5 was about 3 mm less at all ranges.^[34]

Gallery

• 
  Dodge WC-4 prime movers with 37mm gun.
• 
  37mm with its prime mover ready for inspection.
• 
  37mm and Dodge WC-4 in action.
• 
  Loading the gun (crew training, Fort Benning).
• 
  Aiming the gun (crew training, Fort Benning).
• 
  Fort William McKinley

  firing a 37 mm gun in training. Note the lowered wheel segments.
• 
  A dug in 37 mm gun at

  Camp Carson

  .
• 
  The M3 being unloaded from a transport plane during a military demonstration at

  Fort Bragg

  .
• 
  U.S. 37 mm gun crew in action, Saipan, 1944. From left to right are two ammunition carriers, gunner and assistant gunner. Note extended shield.
• 
  HE Mk II Shell and APC M51 Shot.
• 
  TP M51 Shot and 10-gauge adapter M2.

Notes

Notes

Citations

References

• Chamberlain, Peter; Terry Gander (1974). Anti-Tank Weapons. WWII Fact Files. Arco Publishing Company, New York.
  ISBN 0-668-03505-6
  .
• ISBN 1-86126-165-9
  .
• ISBN 0-89141-304-9
  .
• Hunnicutt, R. P. (1992). Stuart, A History of the American Light Tank. Vol. 1. Presidio Press.
  ISBN 0-89141-462-2
  .
• Hunnicutt, R. P. (1994). Sherman: A History of the American Medium Tank. Presidio Press.
  ISBN 0-89141-080-5
  .
• Hunnicutt, R. P. (2001). Half-Track: A History of American Semi-Tracked Vehicles. Presidio Press.
  ISBN 0-89141-742-7
  .
• Hunnicutt, R. P. (2002). Armored Car: A History of American Wheeled Combat Vehicles. Presidio Press.
  ISBN 0-89141-777-X
  .
• Moschanskiy, I. (1999). Armored vehicles of the Great Britain 1939–1945 part 2, Modelist-Konstruktor, Bronekollektsiya 1999–02 (Мощанский, И. (1999). Бронетанковая техника Великобритании 1939–1945 часть 2. Моделист-Конструктор, Бронеколлекция 1999–02.).
• Roberts Jr., Charles C. (2023). The U.S. 37-mm Gun in World War II. Casemate Illustrated Special. Casemate Publishers.
  ISBN 978-1-63624-252-1
  .
• Rottman, Gordon (1995). The US Marine Corps 1941–45. Elite 59. illustrated by Mike Chapell. Osprey Publishing.
  ISBN 1-85532-497-0
  .
• Rottman, Gordon (2004). US Marine Corps Pacific Theater of Operations 1941–43. Battle Orders 1. Osprey Publishing.
  ISBN 1-84176-518-X
  .
• Rottman, Gordon (2006). US Airborne Units in the Mediterranean Theater 1942–44. Battle Orders 22. Osprey Publishing.
  ISBN 1-84176-920-7
  .
• Sayen, John J. (2006). US Army Infantry Divisions 1942–43. Battle Orders 17. Osprey Publishing.
  ISBN 1-84176-952-5
  .
• West, Howard F. (2006). Iron men, wooden boats: the epic story of American PT boats in World War II. Heritage Books.
  ISBN 0-7884-2537-4
  .
• ISBN 1-84176-690-9
  .
• ISBN 978-1-84603-118-2
  .
• ISBN 1-84176-966-5
  .
• Field Manual FM 23-81, 37-mm Gun, Tank, M6. War Department, 1942.
• Technical Manual TM 1-1901, Artillery Ammunition. War Department, 1944.
• Technical Manual TM 9–2005 volume 3, Infantry and Cavalry Accompanying Weapons. War Department, 1942.
• Anderson, Rich. "US Army in World War II; Cavalry and Infantry". militaryhistoryonline.com. Archived from the original on 13 August 2007. Retrieved 27 September 2007.
• "History of U.S. Marine Corps Operations in World War II". HyperWar. Archived from the original on 7 July 2007. Retrieved 1 July 2007.
• "The Marine Division". WW2Gyrene. Archived from the original on 8 June 2019. Retrieved 1 July 2007.
• "M3A1 37mm Antitank Gun". WW2Gyrene. Archived from the original on 22 March 2007. Retrieved 1 July 2007.

External links

Wikimedia Commons has media related to M3 37 mm gun.

• Photo gallery at Fightingiron.com
• Photo gallery at SVSM.org Archived 27 September 2007 at the Wayback Machine.
• Popular Science, April 1940, "Tanks Can Be Destroyed"—article on early US Army concepts for tank destroyers using Gun M3 on various vehicles
• "Little Poison", August 1942, Popular Science—excellent detailed article on the M3 antitank cannon