View source for 37 mm gun M3

{{Short description|American anti-tank gun}}
{{Use dmy dates|date=April 2020}}
{{Infobox weapon
| name = 37mm gun M3 on carriage M4
| image = M-3 Antitank Gun 37mm Towed.jpg
| image_size = 300
| caption = M3 on display at [[Fort Sam Houston]], [[Texas]].
| origin = United States
| type = [[Anti-tank gun]]
<!-- Type selection -->| is_ranged = yes
| is_artillery = yes
| is_vehicle = <!-- Service history -->
| service = 
| used_by = United States<br />[[National Revolutionary Army]]<br />[[Brazil]]<br />[[French Indochina]]<br />[[Viet Minh]]<br />[[National Guard (Nicaragua)|National Guard of Nicaragua]]
| wars = [[World War II]]<br />[[Second Sino-Japanese War]]<br />[[First Indochina War]]<br />[[Nicaraguan Revolution]]
<!-- Production history -->| design_date = 1938
| manufacturer = Gun: [[Watervliet Arsenal]],<br />Carriage: [[Rock Island Arsenal]]
| production_date = 1940–1943
| number = 18,702
| variants = <!-- General specifications -->
| weight = {{convert|912|lb|kg|abbr=on|order=flip}}
| length = {{convert|3.92|m|ftin|1|abbr=on|sigfig=1}}
| width = {{convert|1.61|m|ftin|1|abbr=on|sigfig=1}}
| height = {{convert|0.96|m|ftin|1|abbr=on|sigfig=1}}
| part_length = overall: {{convert|2.1|m|ftin|abbr=on}} L/56.6<br />bore: {{convert|1.98|m|ftin|abbr=on}} L/53.5
| crew = 4–6
<!-- Ranged weapon specifications -->| cartridge = 37×223&nbsp;mm. R
| caliber = 37 mm (1.45 inch)
| action = 
| rate = up to 25 rpm
| velocity = up to 884 m/s (2,900 ft/s)
| range = 
| max_range = {{convert|6.9|km|mi|2|abbr=on}}
| feed = 
| sights = telescopic, M6
<!-- Artillery specifications -->| breech = [[Rifled breech loader#The sliding block|Vertical sliding-block]]
| recoil = [[Hydro-spring]]
| carriage = [[Gun carriage#Modern gun carriages|Split trail]]
| elevation = -10° to +15°
| traverse = 60°
<!-- Explosive specifications -->| diameter = 
| filling = 
| filling_weight = 
| detonation = 
| yield = 
}}
[[File:37-mm-at-gun-fort-benning-3.jpg|thumb|right|Manhandling a gun into position during training at [[Fort Benning]], 1942. Note the raised wheel segments.]]

The '''37&nbsp;mm gun M3''' is the first dedicated [[anti-tank gun]] fielded by United States forces in numbers. Introduced in 1940, it became the standard anti-tank gun of the U.S. [[infantry]] with its size enabling it to be pulled by a [[Willys MB|jeep]]. However, the continuing improvement of [[Nazi Germany|German]] [[tank]]s quickly rendered the 37&nbsp;mm ineffective and, by 1943, it was being gradually replaced in the [[European Theater of Operations|European]] and [[Mediterranean Theater of Operations|Mediterranean]] theaters by the more powerful British-developed [[Ordnance QF 6-pounder|57 mm gun M1]]. In the [[Asiatic-Pacific Theater|Pacific]], where the [[Development of Japanese tanks in World War II|Japanese tank threat]] was less significant, the M3 remained in service until the end of the war, but some 57mm guns were issued.

Like many other light anti-tank guns, the M3 was widely used in the [[Infantry support gun|infantry support]] role and as an anti-personnel weapon, firing [[Shell (projectile)#High-explosive|high-explosive]] and [[canister shot|canister]] rounds.

The M5 and M6 tank mounted variants were used in several models of armored vehicles most notably in the Stuart [[Stuart tank|Light Tank M3/M5]], the Lee [[M3 Lee|Medium Tank M3]], and Greyhound [[M8 Greyhound|Light Armored Car M8]]. In addition, the M3 in its original version was mated to a number of other self-propelled carriages.

The inability of the 37mm round to penetrate the frontal armor of mid-war tanks severely restricted the anti-armor capabilities of units armed with them.

==Development history==
In the mid-1930s, the [[United States Army]] had yet to field a dedicated anti-tank artillery piece; anti-tank [[Company (military unit)|companies]] of infantry [[regiment]]s were armed with {{convert|.50|inch|mm|1|abbr=on}} [[machine gun]]s. Although some consideration had been given to replacing the machine guns with a more powerful [[anti-tank gun]], the situation began to change only after the outbreak of the [[Spanish Civil War]]. Combat experience from Spain suggested that a light anti-tank gun, such as the [[Nazi Germany|German]] [[3.7 cm PaK 36|37 mm PaK 35/36]], was capable of neutralizing the growing threat posed by tanks.<ref name= "ZALOGADELF3to7">Zaloga – ''US Anti-tank Artillery 1941–45'', p. 3–7.</ref>

In January 1937, the [[United States Army Ordnance Corps|Ordnance Committee]] recommended development of such a weapon;<ref name="ZALOGADELF3to7"/> two PaK 36 guns were acquired for study.<ref name="HOGG149">Hogg – ''Allied Artillery of World War Two'', p 149.</ref> As the projected main user of the weapon, the Infantry Branch was chosen to oversee the work. They wanted a lightweight gun that could be moved around by the crew, so any ideas of using a larger caliber than that of the German gun were discarded.<ref name="ZALOGADELF3to7"/> The 37&nbsp;mm was a popular caliber of anti-tank guns in the 1930s; other anti-tank guns of the same caliber included Swedish [[Bofors 37 mm|Bofors gun]], [[Czechoslovakia]]n [[3.7 cm kanon PÚV vz. 34|vz. 34]] and [[3,7cm KPÚV vz. 37|vz. 37]], Japanese [[Type 94 37 mm Anti-Tank Gun|Type 94]] and [[Type 1 37 mm Anti-Tank Gun|Type 1]].

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&nbsp;mm gun M3 and carriage M4.<ref name="ZALOGADELF3to7"/> Although the weapon followed the concept of the PaK 36 and was often referred to as a copy of it,<ref>E.g. see Rottman – ''The US Marine Corps 1941–45'', p 17: "M3A1 ... was copied from the standard German AT gun" or Sayen – ''US Army Infantry Divisions 1942–43'', p 13: "M3 or M3A1 towed guns were unlicensed versions of the German Pak 35/36".</ref> 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 ([[Canon d'Infanterie de 37 modèle 1916 TRP|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.<ref>{{cite book|date=1947|title=Official Munitions Production of the United States by Months, July 1, 1940-August 31, 1945|location=Washington, D.C.|publisher=War Production Board|page=139}}</ref><ref name="ZALOGADELF3to7"/><ref>{{cite news|date= October 28, 1941|title=New Guns for the 35th|work=Kansas City Times|location=Kansas City, MO}}</ref>

{| class="wikitable"
|+ Production of М3, numbers of pieces<ref>Zaloga – ''US Anti-tank Artillery 1941–45'', page 21.</ref><ref>{{cite book|date=1947|title=Official Munitions Production of the United States by Months, July 1, 1940-August 31, 1945|location=Washington, D.C.|publisher=War Production Board|page=139}}</ref>
|-
! Month !! 1940 !! 1941 !! 1942 !! 1943
|-
| January || || 40 || 609 || 894
|-
| February || || || 639 || 625
|-
| March || || 2 || 394 || 452
|-
| April || || 57 || 752 || 290
|-
| May || || 12 || 1,002 || 200
|-
| June || || 63 || 962 || 400
|-
| July || 20 || 72 || 921 || 600
|-
| August || 75 || 188 || 1,104 || 500
|-
| September || 75 || 366 || 1,099 || 152
|-
| October || 128 || 555 || 1,501 || 185
|-
| November || 31 || 451 || 1,338 ||
|-
| December || 11 || 446 || 1,491 ||
|-
! Total !! 340 !! 2,252 !! 11,812 !! 4,298
|}

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.<ref name="ZALOGADELF3to7"/> Another change was a threaded [[Gun barrel|barrel]] end to accept a big five-port [[muzzle brake]] (gun M3A1, adopted on 5 March 1942). According to some sources, the latter was intended to avoid kicking too much dust in front of the gun, which hindered aiming; however, the brake turned out to be a safety problem when firing [[Case shot|canister ammunition]] and consequently the M3A1 went into combat without the muzzle brake.<ref name= "ZALOGADELF3to7"/> Other sources state that the muzzle brake was intended to soften the recoil, and that it was dropped simply because additional recoil control measures were not really needed.<ref name="HOGG149"/><ref name="CHAMBERLAINGANDER47">Chamberlain, Gander – ''Anti-Tank Weapons'', page 47.</ref>

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. {{convert|4.5|in|mm|abbr=on}} rocket projector T3) did not produce anything practical either.<ref name="ZALOGADELF3to7"/>

==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.<ref name=TM-9-2005>''Technical Manual TM 9-2005 volume 3, Infantry and Cavalry Accompanying Weapons'', pages 11-15.</ref>

The carriage was of [[Gun carriage#Modern gun carriages|split trail]] type, with pneumatic tires but without any spring suspension whatsoever.<ref name=TM-9-2005/> 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.<ref name=TM-9-2005/>

==Organization==
[[File:Front line of Kwajalein.jpg|thumb|right|Men of the [[7th Infantry Division (United States)|7th Division, US Army]] move a gun up to the front line on [[Battle of Kwajalein|Kwajalein]].]]

===US Army===
Under the April 1942 organization, each infantry [[battalion]] had an anti-tank [[platoon]] with four 37&nbsp;mm guns ([[Willys MB|1/4 ton trucks]], better known as jeeps, were authorized as prime movers) and each [[regiment]] an anti-tank [[Company (military unit)|company]] with twelve (towed by [[Dodge WC series|3/4 ton trucks]]). Each of the four divisional artillery battalions possessed six anti-tank guns, the combat engineering battalion had nine pieces (towed by [[M2 Half Track Car|M2 halftrack]]s); in addition, the division's headquarters company had four (towed by 3/4&nbsp;ton trucks) and the divisional maintenance company two.<ref name="SAYEN">Sayen – ''US Army Infantry Divisions 1942–43'', pages 9, 15, 25, 28, 33, 36.</ref>
[[File:Stuart m5a1 cfb borden 4.JPG|thumb|right|A 37 mm gun on a [[Stuart tank|M5A1 Stuart tank]]]]

In 1941, provisional antitank battalions had been formed from divisional or brigade anti-tank weapons (producing companies armed with 37&nbsp;mm guns and [[Canon de 75 modèle 1897|75 mm gun]]s), in December 1941, these battalions became permanent and were reorganized as independent [[tank destroyer battalions (United States)|tank destroyer battalions]]. The towed guns of many battalions were replaced with self-propelled ones as soon as the latter became available.<ref name="ZALOGADELF9to12">Zaloga – ''US Anti-tank Artillery 1941–45'', pages 9-12.</ref>

In 1942, the first airborne divisions were formed. According to their October 1942 organizational structure, an airborne division had 44 37&nbsp;mm anti-tank guns: four in divisional artillery (AA/AT battery of parachute field artillery battalion), 24 in the AA/AT battalion, and eight in each of two [[glider infantry]] regiments; [[parachute infantry]] regiments did not have anti-tank guns. In practice, airborne divisions often had only one glider infantry regiment and therefore 36 guns.<ref>Rottman – ''US Airborne Units in the Mediterranean Theater 1942–44'', pages 30-39; Zaloga – ''US Airborne Divisions in the ETO 1944–45'', pages 16-25, 33, 41.</ref>

37&nbsp;mm guns were also issued to the infantry regiments of the only mountain division formed in the U.S.: the [[10th Mountain Division (United States)|10th Mountain Division]].<ref name= "ANDERSON">Anderson – ''US Army in World War II; Cavalry and Infantry''.</ref>

Finally, U.S. armored divisions under the March 1942 organization possessed 68 37&nbsp;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.<ref>Zaloga – ''US Armored Units in the North African and Italian Campaigns 1942–45'', pages 24-28.</ref>

===US Marine Corps===
Under the D-series Tables of Organization (TO) from 1 July 1942, the role of AT weapons in [[United States Marine Corps|Marine Corps]] service was officially entrusted to 20&nbsp;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 [[Canon d'Infanterie de 37 modèle 1916 TRP|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 [[M6 Gun Motor Carriage|37 mm GMC M6]].<ref>Rottman – ''US Marine Corps Pacific Theater of Operations 1941–43'', pages 25-30.</ref>

Under the E-series TO from 15 April 1943, self-propelled guns in the divisional special weapons battalion were replaced with eighteen 37&nbsp;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.<ref>History of U.S. Marine Corps Operations in World War II, Vol II: Table of Organization E-100, p 571, 572; Vol III: Table of Organization F-100, p 618, 619; Rottman – ''The US Marine Corps 1941–45'', pages 5-8; ww2gyrene: The Marine Division; ww2gyrene: M3A1 37mm Antitank Gun.</ref>

===Other operators===
The only major [[lend lease]] recipient of the M3 was the Chinese [[National Revolutionary Army]] (1,669 pieces). The gun was also supplied to Bolivia (4), Canada (3), Chile (198), Colombia (4), Cuba (1), El Salvador (9), France (130), Paraguay (12), United Kingdom (78), Soviet Union (63), Nicaragua (9), and other countries.<ref>Zaloga – ''US Anti-tank Artillery 1941–45'', page 44.</ref> Some nations still had it in service in the early 1970s.<ref name="CHAMBERLAINGANDER47"/>

==Combat service==
===As an infantry anti-tank gun===
[[File:Japanese-tanks-matanikau.gif|thumb|right|Japanese tanks knocked out by 37 mm guns near the mouth of the [[Matanikau River]], Guadalcanal.]]
[[File:37mm Gun fires against cave positions at Iwo Jima.jpg|thumb|right|The M3 fires against Japanese cave positions in at [[Battle of Iwo Jima|Iwo Jima]]. Note modified shield with irregular top edge.]]

The M3 saw action for the first time during the [[Battle of the Philippines (1941-42)|defense of the Philippines]] in December 1941.<ref name="ZALOGADELF9to12"/> It went on to become a factor in the [[Guadalcanal Campaign]], where it was successfully employed against both Japanese armor and infantry.<ref>History of U.S. Marine Corps Operations in World War II, Volume I: The Battle of the Tenaru, page 290; Volume I: Japanese Counteroffensive, pages 330 & 332.</ref> Throughout the war it remained effective against Japanese vehicles, which were thinly armored and were rarely committed in large groups. The light weight of the gun made it easy to move through difficult terrain; for example, when attacked by Japanese tanks on Betio during the [[Battle of Tarawa]], Marines were able to heave the M3 over the {{convert|5|ft|m|abbr=on}}-high seawall.<ref name="ROTTMANCHAPELL12">Rottman – ''The US Marine Corps 1941–45'', pages 12-13.</ref> While [[high-explosive]] and [[canister shot|canister ammunition]] proved useful in stopping Japanese infantry attacks, against enemy fortifications the M3 was only somewhat effective because of its small high-explosive projectile. Its overall effectiveness and ease of use meant the gun remained in service with the Marine Corps and with some army units in the Pacific until the end of the war.<ref name="ZALOGADELF9to12"/> Unhappy with the unusually low shield of the M3, some Marine Corps units extended it to provide better protection. These extensions sometimes had a scalloped top edge, intended to improve camouflage. A standard kit was tested in 1945, but was never issued.<ref>Zaloga, ''US Anti-tank Artillery 1941–45'', pages 6 & 46.</ref>

The experience of the M3 in the [[North African Campaign]] was completely different. The gun was not powerful enough to deal with late production German [[Panzer III|''Panzer'' III]] and [[Panzer IV|IV]] tanks. After the nearly disastrous [[Battle of Kasserine Pass]] in February 1943, reports from some of the involved units mentioned 37&nbsp;mm projectiles "bouncing off like marbles" from the turret and front armor of German medium tanks and proclaimed the gun "useless unless you have gun crews with the guts to stand and shoot from 100&nbsp;yards".<ref name="ZALOGADELF9to12"/> The Army was initially uncertain if these reports reflected the obsolescence of the weapon, or whether unrefined tactics and lack of experience were to blame.<ref group=note>The situation mirrored German  experience with their [[3.7 cm Pak 36]], which was nicknamed ''Heeresanklopfgerät'' (literally "army door-knocking device") by its crews for its inability to affect Soviet T-34 tanks aside from notifying its presence by futilely bouncing rounds off its armour, regardless of the angle or distance.</ref> Yet, on 26 May 1943, a new organization had the M3 replaced by the 57&nbsp;mm Gun M1 (the U.S.-produced version of the British [[Ordnance QF 6 pounder|6-pounder gun]]),<ref group="note">In service with the [[British Army]] since 1942</ref> with Dodge 1½ ton trucks as prime movers. Only by spring 1944 did the 57&nbsp;mm gun reach the battlefield in large numbers.<ref name="ZALOGADELF9to12"/>

Meanwhile, the [[Italian Campaign (World War II)|Italian campaign]] was launched, and M3 guns saw action from the day of the [[Allied invasion of Sicily|Sicily landing]] on 10 July 1943. That day the 37&nbsp;mm guns demonstrated once again both their effectiveness against pre-war tanks—when they helped to repel an attack by Italian [[Renault R 35]]s—and inability to cope with modern threats in a subsequent encounter with [[Tiger I]]s from the [[Fallschirm-Panzer Division 1 Hermann Göring|''Hermann Göring'' division]]. The Italian theater had a lower priority for reequipment than Northwest Europe, and some M3s were still in use in Italy in late 1944.<ref>Zaloga, ''US Anti-tank Artillery 1941–45'', pages 21 & 22.</ref>

By mid-1944, the M3 had fallen out of favor even with airborne troops, despite their strong preference for compact and lightweight weapon systems. The Airborne Command had rejected the 57&nbsp;mm M1 in the summer of 1943 claiming its unfitness for airlifting<ref>Zaloga – ''US Anti-tank Artillery 1941–45'', page 15.</ref> and the Table of Organisation and Equipment (TO&E) of February 1944 still had airborne divisions keeping their 37&nbsp;mm guns. Nevertheless, the [[U.S. 82nd Airborne Division|82nd]] and [[101st Airborne Division|101st]] Airborne Divisions were reequipped with British-manufactured 6-pounder gun (57&nbsp;mm) on carriage Mk III (designed to fit into the British [[Airspeed Horsa|Horsa glider]]) for the [[Normandy Landings#Airborne operations|Normandy airdrops]]. This change was officially introduced in the TO&E of December 1944.<ref>Zaloga, ''US Airborne Divisions in the ETO 1944–45'', pages 16–25, 33, & 41; Zaloga, ''US Anti-tank Artillery 1941–45'', page 23.</ref>

===As a tank gun===
{{Quote box
| quote = The 37mm gun is essentially an antimechanized weapon... 37mm guns will be disposed to protect the flanks and rear of the (Cavalry Reconnaissance) Squadron against mechanized attack and also, in the base of fire, to support the attack. Armor-piercing ammunition is effective against mechanized vehicles, matérial, and weapons. High Explosive ammunition is effective against personnel, light matérial, automatic weapons, and mortars.
| source = – ''FM 2-30 Cavalry Field Manual - Cavalry Mechanized Reconnaissance Squadron'', March 29, 1943, Page 71.<ref>{{cite web |title=FM 2-30 Cavalry Field Manual - Cavalry Mechanized Reconnaissance Squadron |url=https://ia800301.us.archive.org/27/items/Fm2-30/Fm2-30.pdf |date=29 March 1943}}</ref>
| width = 35%
| align = right
}}
The 37mm gun was used as the primary armament for [[M3 Stuart|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.

There were also serious issues with the gun's ability to function effectively in the infantry support role.<ref>{{cite journal|url=http://digicom.bpl.lib.me.us/ww_reg_his/60/|title="752nd Tank Bn", World War Regimental Histories|journal=World War Regimental Histories |year=1945|publisher=United States Army|pages=60 of 85|access-date=16 June 2018}}</ref> The 37mm HE round had 39 grams (0.085 lb) of TNT, producing an explosive power of 161 Kilojoules.<ref>{{cite book|url=https://books.google.com/books?id=NeYDDQAAQBAJ|title=The American Arsenal: The World War II Official Standard Ordnance Catalogue|year=2001|pages=266|isbn=9781473897038|access-date=25 April 2019|last1=Hogg|first1=Ian V.}}</ref><ref>{{cite web|url=https://archive.org/details/Tm9-1901|title=Complete Round Table for ammunition for 37mm guns (M63/TNT)|year=1944|work=TM 9-1901 Artillery Ammunition, 1944|access-date=16 June 2018}}</ref> By way of contrast, the HE round from a Sherman [[75 mm Gun M2/M3/M6|75mm gun]] had 667 grams (1.47 lb) of TNT, producing 2790 Kilojoules, while the modern [[40 mm grenade|40mm shell]] from M203 [[M203 grenade launcher|grenade launchers]] has 32 grams (0.07 lb) of Comp B, producing an explosive power of 134 Kilojoules.<ref>{{cite web|url=https://archive.org/details/milmanual-tm-43-0001-28-army-ammunition-data-sheets|title=CARTRIDGE, 40-MILLIMETER: HE, M381|year=1994|work=TM 43-0001-28 Army Ammunition Data Sheets|pages=574–575 of 913|access-date=16 June 2018}}</ref>

The M3 was phased out of U.S. service soon after the end of the war.<ref name= "CHAMBERLAINGANDER47"/>

==Variants==
*Test variants:
**T3 – the first prototype.<ref name="ZALOGADELF3to7"/>
**T7 – a prototype with semi-automatic horizontal [[Rifled breech loader#The sliding block|sliding-block]] breech.<ref name="HOGG149"/>
**T8 – a prototype with [[Thorsten Nordenfelt|Nordenfelt]] eccentric screw breech.<ref name= "HOGG149"/>
**T10 – standardized as M3 (1938) – an adopted version, with manual vertical block breech.<ref name ="ZALOGADELF3to7"/><ref name="HOGG149"/>
*Model variants
**M3 towed version, manual breech.
***M3A1 (1942) – version with threaded barrel end to accept a muzzle brake, which was never issued.<ref name="ZALOGADELF3to7"/>
**M5 (1939) – tank mounted variant with shorter barrel.<ref name="HUNNICUTT-STUART-118and143">Hunnicutt – ''Stuart: A History of the American Light Tank'', p 118, 143.</ref>
**M6 (1940) – tank mounted variant with barrel of the original length and with semi-automatic breech.<ref name="HUNNICUTT-STUART-118and143"/>
*Carriage variants:
**T1, T1E1 – prototypes.<ref name="ZALOGADELF3to7"/>
**T5, standardized as M4 – first adopted version.<ref name="ZALOGADELF3to7"/>
**M4A1 (1942) – carriage with improved traverse controls.<ref name="ZALOGADELF3to7"/>
**In 1942, the Airborne Command requested a version with removable trails. A prototype was tested, but in 1943 the project was dropped as unnecessary.<ref name="ZALOGADELF3to7"/>

At least in one case, [[United States Fifth Army|Fifth Army]] Ordnance in Italy fitted the gun experimentally with fifteen {{convert|4.5|in|mm|abbr=on}} aircraft rockets, in five clusters of three, mounted above the shield.<ref>Zaloga, ''US Anti-tank Artillery 1941–45'', page 14.</ref>

Variants of the M3 should not be confused with other 37&nbsp;mm guns in the U.S. service. Those other pieces included the [[37 mm M1916|M1916]] infantry gun of French design (these were later used extensively as [[subcaliber training|subcaliber devices]] for heavy artillery.),<ref>{{Cite book |title=TM 9-2300. Standard Artillery and Position Finding Equipment |year=1944}}</ref> [[37mm Gun M1|M1]] antiaircraft autocannon, [[M4 cannon|M4/M9/M10]] aircraft-mounted autocannons, M12/M13/M14/M15 subcaliber guns.

==Self-propelled mounts==
[[File:A-FM-23-80-37mm-Gun-M5-left.jpg|right|thumb|37mm Gun M5, as mounted in Light Tank M2A4.]]
[[File:M6-37mm-GMC.jpg|right|thumb|37mm GMC M6 with improvised machine gun mount.]]

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 {{convert|5.1|in|mm|abbr=on}} 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.<ref name= "HUNNICUTT-STUART-118and143"/> These guns were mounted on several models of tanks and other armored vehicles:
*[[M2 Light Tank|Light Tank M2A4]]: M5 in mount M20. The recoil mechanism, protruding beyond the gun mask, had to be protected by an armored casing.<ref>Hunnicutt – ''Stuart: A History of the American Light Tank'', p 119, 143.</ref>
*[[Stuart tank|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.<ref>Hunnicutt – ''Stuart: A History of the American Light Tank'', pages 127, 143.</ref>
*[[Stuart tank|Light Tank M3A1, M5]]: M6 in mount M23.<ref name="HUNNICUTT-STUART-496">Hunnicutt – ''Stuart: A History of the American Light Tank'', page 496.</ref>
*[[Stuart tank|Light Tank M3A3, M5A1]]: M6 in mount M44.<ref name="HUNNICUTT-STUART-496"/>
*[[M22 Locust|Light Tank (Airborne) M22]]: M6 in mount M53.<ref>Hunnicutt – ''Stuart: A History of the American Light Tank'', page 484.</ref>
*[[Lee tank|M3 series medium tanks]] (as a secondary weapon): M5 or M6 in mount M24.<ref name="HUNNICUTT-SHERMAN-528">Hunnicutt – ''Sherman: A History of the American Medium Tank'', page 528.</ref>
*[[M6 Heavy Tank|Heavy Tank M6]] (as a secondary weapon): M6 in mount T49.<ref>Hunnicutt – ''Firepower: A History of the American Heavy Tank'', pages 193, 194.</ref>
*[[Landing Vehicle Tracked|LVT(A)-1 {{not a typo|"amtank"}}]]: M6 in mount M44.<ref name="HUNNICUTT-STUART-496"/>
*37&nbsp;mm Gun Motor Carriage T22 – eventually [[M8 Greyhound|Light Armored Car M8]]: M6 in mount M23A1; the competing designs 37&nbsp;mm Gun Motor Carriage T43 / Light Armored Car T21 and 37&nbsp;mm Gun Motor Carriage T23 / Light Armored Car T23 mounted the same weapon.<ref name= "HUNNICUTT-AC-108, 319">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 108.</ref>
*Armored Car T13.<ref name="HUNNICUTT-AC-71">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', pages 71, 73.</ref>
*[[T17 Deerhound|Armored Car T17]]: M6 in mount M24.<ref name="HUNNICUTT-AC-315">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 315.</ref>
*[[T17E1 Staghound|Armored Car T17E1]] in the "Staghound Mk I" configuration: M6 in mount M24A1.<ref name="HUNNICUTT-AC-316">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 316.</ref>
*The first pilot of the [[T18 Boarhound|Armored Car T18]]: M6. The production variant T18E2 received the 57mm M1.<ref name="HUNNICUTT-AC-98">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 98.</ref>
*Armored Car T19: M6 in mount M23A1.<ref name="HUNNICUTT-AC-324">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 324.</ref>
*[[T27 Armored Car|Armored Car T27]]: M6 in mount M23A1 modified.<ref name="HUNNICUTT-AC-322">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', p 322.</ref>
*[[M38 Wolfhound|Armored Car T28 / M38]]: M6 in mount M23A2.<ref name="HUNNICUTT-AC-323">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 323.</ref>
*British [[Humber Armoured Car|Humber Armoured Car Mk IV]]: M6.<ref>Moschanskiy – ''Armored vehicles of the Great Britain 1939–1945 part 2'', page 9.</ref>

Versions of the gun in turret mounts were also used in the [[Medium Tank T5|Medium Tank T5 Phase III]] (T3 barrel, mount T1),<ref>Hunnicutt – ''Sherman: A History of the American Medium Tank'', p 34.</ref> in the [[M2 Medium Tank|Medium Tank M2 / M2A1]] (M3 barrel, M2A1: mount M19),<ref>Hunnicutt – ''Sherman: A History of the American Medium Tank'', pages 36, 40.</ref> and in the 37mm Gun Motor Carriage T42 (mount M22).<ref>Hunnicutt – ''Stuart: A History of the American Light Tank'', page 303.</ref>
[[File:1942Jeep.jpg|right|thumb|Soldiers of the [[3rd United States Infantry Regiment|U.S. 3rd Infantry]] on maneuvers, 1942. Their Willys / Ford jeep is fitted with M3 on a pedestal mount.]]

In addition, the M3 on different pedestal mounts was mated to a number of other vehicles, resulting in an assortment of 37&nbsp;mm gun motor carriages. Only the [[M6 Fargo|M6]] reached mass production.
*37&nbsp;mm Gun Motor Carriage T2 ([[Willys MB|Bantam jeep]]).<ref name="HUNNICUTT-AC-152">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 152.</ref>
*37&nbsp;mm Gun Motor Carriage T8 (Ford 4x4 "Swamp Buggy").<ref name="HUNNICUTT-AC-153">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 153.</ref>
*37&nbsp;mm Gun Motor Carriage T13, T14 (Willys 6x6 "Super Jeep").<ref name="HUNNICUTT-AC-158">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 158.</ref>
*[[M6 Fargo|37 mm Gun Motor Carriage T21 / M4 / M6]] (Fargo 3/4 ton 4x4 truck).<ref name="HUNNICUTT-AC-154">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', pages 154, 155.</ref>
*37&nbsp;mm Gun Motor Carriage T33 (Ford 3/4 ton 4x4 cargo carrier).<ref name="HUNNICUTT-AC-160">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 160.</ref>
*[[M3 Scout Car|M3A1E3 Scout Car]].<ref name="HUNNICUTT-AC-58">Hunnicutt – ''Armored Car: A History of American Wheeled Combat Vehicles'', page 58.</ref>
*The gun was sometimes mounted on [[M2 Half Track Car|M2 Halftrack]],<ref name="HUNNICUTT-HT-230">Hunnicutt – ''Half-Track: A History of American Semi-Tracked Vehicles'', page 230.</ref> [[M29 Weasel]]<ref name="CHAMBERLAINGANDER47"/> and on the [[Willys MB|1/4 ton Willys MB / Ford GPW jeep]] (see photo on the right).

On several occasions, the M3 was mounted on [[PT boat]]s to increase their firepower. One of these boats was [[John F. Kennedy]]'s [[Motor Torpedo Boat PT-109|PT-109]]. The gun with its wheels removed was mounted on wooden planks nailed to the deck.<ref>West – ''Iron men, wooden boats'', page 146.</ref>

==Ammunition==
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.<ref>{{cite web | url=https://www.tankarchives.ca/2017/09/lend-lease-impressions-37-mm-m3-anti.html | title=Lend Lease Impressions: 37 mm M3 Anti-Tank Gun }}</ref>

{| class="wikitable"
|- style="vertical-align:top; text-align:center; border:1px solid #996; background-color:#996; color:#fff"
|+Available ammunition<ref name="HUNNICUTT-STUART-496"/><ref>''Field Manual FM 23–81, 37-mm Gun, Tank, M6'', pages 45-51.</ref><ref>''Technical Manual TM 1–1901'', Artillery Ammunition.</ref>
|- style="vertical-align:top; text-align:center; border:1px solid #996;"
!width="20%" style="border:1px solid #996" | Type
!width="20%" style="border:1px solid #996" | Model
!width="20%" style="border:1px solid #996" | Weight, kg (round/projectile)
!width="20%" style="border:1px solid #996" | Filler
!width="20%" style="border:1px solid #996" | Muzzle velocity, m/s (M3&M6/M5)
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | [[Armor-piercing shot and shell|AP-T]]
|style="border:1px solid #996" | AP M74 Shot
|style="border:1px solid #996" | 1.51 / 0.87
|style="border:1px solid #996" | –
|style="border:1px solid #996" | 884 / 870
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | APCBC-T
|style="border:1px solid #996" | APC M51 Shot
|style="border:1px solid #996" | 1.58 / 0.87
|style="border:1px solid #996" | –
|style="border:1px solid #996" | 884 / 870
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | [[Shell (projectile)#High-explosive|HE]]
|style="border:1px solid #996" | HE M63 Shell
|style="border:1px solid #996" | 1.42 / 0.73
|style="border:1px solid #996" | [[Trinitrotoluene|TNT]], 39 g
|style="border:1px solid #996" | 792 / 782
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | HE
|style="border:1px solid #996" | HE Mk II Shell
|style="border:1px solid #996" | 1.23 / 0.56
|style="border:1px solid #996" | [[Trinitrotoluene|TNT]], 27 g
|style="border:1px solid #996" |
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | [[Canister shot|Canister]]
|style="border:1px solid #996" | Canister M2
|style="border:1px solid #996" | 1.58 / 0.88
|style="border:1px solid #996" | 122 steel balls
|style="border:1px solid #996" | 762 / 752
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | Target practice with tracer
|style="border:1px solid #996" | TP M51 Shot
|style="border:1px solid #996" | 1.54 / 0.87
|style="border:1px solid #996" | –
|style="border:1px solid #996" |
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | Drill (simulates APC M51)
|style="border:1px solid #996" | Drill Cartridge M13
|style="border:1px solid #996" | 1.45 / 0.87
|style="border:1px solid #996" | –
|style="border:1px solid #996" | –
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | Drill (simulates HE M63)
|style="border:1px solid #996" | Drill Cartridge T5
|style="border:1px solid #996" | 1.45 / 0.73
|style="border:1px solid #996" | –
|style="border:1px solid #996" | –
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | Blank
|style="border:1px solid #996" | Blank Cartridge 10-[[Gauge (bore diameter)|gauge]] with adapter M2
|style="border:1px solid #996" | 0.93 / –
|style="border:1px solid #996" | –
|style="border:1px solid #996" | –
|}

:&nbsp;
:

{| class="wikitable"
|- style="vertical-align:top; text-align:center; border:1px solid #996; background-color:#996; color:#fff"
|+ Armor penetration, M3 or M6, millimeters
|- style="vertical-align:top; text-align:center; border:1px solid #996;"
!width="44%" style="border:1px solid #996" | Ammunition \ Distance, yd / m
!width="14%" style="border:1px solid #996" | 500 / 457
!width="14%" style="border:1px solid #996" | 1,000 / 914
!width="14%" style="border:1px solid #996" | 1,500 / 1,371
!width="14%" style="border:1px solid #996" | 2,000 / 1,828
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | AP M74 Shot (meet angle 0°)<ref name="HOGG149"/>
|style="border:1px solid #996" | 36
|style="border:1px solid #996" |
|style="border:1px solid #996" |
|style="border:1px solid #996" |
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | AP M74 Shot (meet angle 20°)<ref name= "CHAMBERLAINGANDER47"/>
|style="border:1px solid #996" |
|style="border:1px solid #996" | 25
|style="border:1px solid #996" |
|style="border:1px solid #996" |
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | APC M51 Shot (meet angle 0°)<ref name="HOGG149"/>
|style="border:1px solid #996" | 61
|style="border:1px solid #996" |
|style="border:1px solid #996" |
|style="border:1px solid #996" |
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | APC M51 Shot (meet angle 20°)<ref name= "CHAMBERLAINGANDER47"/>
|style="border:1px solid #996" |
|style="border:1px solid #996" | 53
|style="border:1px solid #996" |
|style="border:1px solid #996" |
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | APC M51 Shot (meet angle 30°, homogeneous armor)<ref name="HUNNICUTT-STUART-496"/>
|style="border:1px solid #996" | 53
|style="border:1px solid #996" | 46
|style="border:1px solid #996" | 40
|style="border:1px solid #996" | 35
|- style="vertical-align:top; text-align:center;"
|style="border:1px solid #996; text-align:left" | APC M51 Shot (meet angle 30°, face-hardened armor)<ref name="HUNNICUTT-STUART-496"/>
|style="border:1px solid #996" | 46
|style="border:1px solid #996" | 40
|style="border:1px solid #996" | 38
|style="border:1px solid #996" | 33
|- style="vertical-align:top; text-align:center;"
|colspan="5" | Different methods of armor penetration measurement were used in different countries / periods. Therefore, direct comparison is often impossible.
|}

Armor penetration of the M5 was about 3&nbsp;mm less at all ranges.<ref name="HUNNICUTT-STUART-496"/>

==Gallery==
<gallery>
File:Dodge WC-4 prime mover.jpg|Dodge WC-4 prime movers with 37mm gun.
File:Camp carson 37mm.jpeg|37mm with its prime mover ready for inspection.
File:37mm gun prime mover.jpg|37mm and Dodge WC-4 in action.
Image:37-mm-at-gun-fort-benning-4.jpg|Loading the gun (crew training, Fort Benning).
Image:37-mm-at-gun-fort-benning-2.jpg|Aiming the gun (crew training, Fort Benning).
Image:Philippine Scouts at Fort McKinley.jpg|[[Philippine Scouts]] at [[Fort William McKinley]] firing a 37 mm gun in training. Note the lowered wheel segments.
Image:37 m-m anti-tank gun at Camp Carson training camp in Colorado - NARA - 197170.jpg|A dug in 37 mm gun at [[Camp Carson]].
Image:Fort Bragg, North Carolina. Unloading a 37mm gun from a transport plane in a military demonstration.jpg|The M3 being unloaded from a transport plane during a military demonstration at [[Fort Bragg, North Carolina|Fort Bragg]].
Image:37mm gun crew in battle lg.jpg|U.S. 37 mm gun crew in action, [[Battle of Saipan|Saipan]], 1944. From left to right are two ammunition carriers, gunner and assistant gunner. Note extended shield.
Image:A-FM-23-81-37mm-ammo-1.jpg|HE Mk II Shell and APC M51 Shot.
Image:A-FM-23-81-37mm-ammo-2.jpg|TP M51 Shot and 10-gauge adapter M2.
</gallery>

==Notes==
;Notes
{{reflist |group=note}}
;Citations
{{reflist}}

==References==
*{{cite book | last = Chamberlain | first = Peter |author2= Terry Gander | title = Anti-Tank Weapons | publisher = Arco Publishing Company, New York | series = WWII Fact Files | year = 1974 | isbn = 0-668-03505-6}}
*{{cite book | last = Hogg | first = Ian V. | author-link = Ian V. Hogg | title = Allied Artillery of World War Two | publisher = Crowood Press, Ramsbury | year = 1998 | isbn = 1-86126-165-9}}
*{{cite book | last = Hunnicutt | first = R. P. | author-link =R. P. Hunnicutt | title = Firepower: A History of the American Heavy Tank. | publisher = Presidio Press | year = 1988 | isbn = 0-89141-304-9}}
*{{cite book |last= Hunnicutt |first= R. P. |title=Stuart, A History of the American Light Tank |volume=1 |year =1992 |publisher= Presidio Press |isbn= 0-89141-462-2 |url= https://archive.org/details/historyofamerica0000hunn}}
*{{cite book | last = Hunnicutt | first = R. P. | title = Sherman: A History of the American Medium Tank. | publisher = Presidio Press | year = 1994 | isbn = 0-89141-080-5}}
*{{cite book | last = Hunnicutt | first = R. P. | title = Half-Track: A History of American Semi-Tracked Vehicles. | publisher = Presidio Press | year = 2001 | isbn = 0-89141-742-7}}
*{{cite book | last = Hunnicutt | first = R. P. | title = Armored Car: A History of American Wheeled Combat Vehicles. | publisher = Presidio Press | year = 2002 | isbn = 0-89141-777-X}}
*Moschanskiy, I. (1999). ''Armored vehicles of the Great Britain 1939–1945 part 2'', Modelist-Konstruktor, Bronekollektsiya 1999–02 ({{cite book | last = Мощанский | first = И. | title = Бронетанковая техника Великобритании 1939–1945 часть 2 | series = Моделист-Конструктор, Бронеколлекция 1999–02 | year = 1999}}).
*{{cite book | last = Roberts Jr. | first = Charles C. | title = The U.S. 37-mm Gun in World War II | publisher = Casemate Publishers| series = Casemate Illustrated Special| year = 2023 | isbn = 978-1-63624-252-1}}
*{{cite book | last = Rottman | first = Gordon | others = illustrated by Mike Chapell | title = The US Marine Corps 1941–45 | publisher = Osprey Publishing | series = Elite 59 | year = 1995 | isbn = 1-85532-497-0}}
*{{cite book | last = Rottman | first = Gordon |  title = US Marine Corps Pacific Theater of Operations 1941–43 | publisher = Osprey Publishing | series = Battle Orders 1 | year = 2004 | isbn = 1-84176-518-X}}
*{{cite book | last = Rottman | first = Gordon |  title = US Airborne Units in the Mediterranean Theater 1942–44 | publisher = Osprey Publishing | series = Battle Orders 22 | year = 2006 | isbn = 1-84176-920-7 }}
*{{cite book | last = Sayen | first = John J. | title = US Army Infantry Divisions 1942–43 | publisher = Osprey Publishing | series = Battle Orders 17 | year = 2006 | isbn = 1-84176-952-5}}
*{{cite book | last = West | first = Howard F. | title = Iron men, wooden boats: the epic story of American PT boats in World War II | publisher = Heritage Books | year = 2006 | isbn = 0-7884-2537-4}}
*{{cite book | last = Zaloga | first = Steven J. | author-link = Steven Zaloga | others = illustrated by Brian Delf | title = US Anti-tank Artillery 1941–45 | publisher = Osprey Publishing | series = New Vanguard 107 | year = 2005 | isbn = 1-84176-690-9}}
*{{cite book | last = Zaloga | first = Steven J. | author-link = Steven Zaloga | title = US Airborne Divisions in the ETO 1944–45 | publisher = Osprey Publishing | series = Battle Orders 25 | year = 2007 | isbn = 978-1-84603-118-2}}
*{{cite book | last = Zaloga | first = Steven J. | author-link = Steven Zaloga | title = US Armored Units in the North African and Italian Campaigns 1942–45 | publisher = Osprey Publishing | series = Battle Orders 21 | year = 2006 | isbn = 1-84176-966-5}}
*{{cite book | title = Field Manual FM 23-81, 37-mm Gun, Tank, M6 | publisher = War Department, 1942}}
*{{cite book | title = Technical Manual TM 1-1901, Artillery Ammunition | publisher = War Department, 1944}}
*{{cite book | title = Technical Manual TM 9–2005 volume 3, Infantry and Cavalry Accompanying Weapons | publisher = War Department, 1942}}
*{{cite web | last=Anderson | first=Rich | title=US Army in World War II; Cavalry and Infantry | url=http://www.militaryhistoryonline.com/wwii/usarmy/cavalry.aspx | publisher=militaryhistoryonline.com | access-date=2007-09-27 | archive-url= https://web.archive.org/web/20070813224327/http://www.militaryhistoryonline.com/wwii/usarmy/cavalry.aspx| archive-date= 13 August 2007 | url-status= live}}
*{{cite web | title=History of U.S. Marine Corps Operations in World War II | url=http://www.ibiblio.org/hyperwar/USMC/ | publisher=HyperWar | access-date=2007-07-01 | archive-url= https://web.archive.org/web/20070707115000/http://www.ibiblio.org/hyperwar/USMC/| archive-date= 7 July 2007 | url-status= live}}
*{{cite web | title=The Marine Division | url=http://www.ww2gyrene.org/Division_structure.htm | publisher=WW2Gyrene | access-date=2007-07-01 | archive-url=https://web.archive.org/web/20190608093126/http://www.ww2gyrene.org/Division_structure.htm | archive-date=8 June 2019 | url-status=dead}}
*{{cite web | title=M3A1 37mm Antitank Gun | url=http://www.ww2gyrene.org/weapons_37mm.htm | publisher=WW2Gyrene | access-date=2007-07-01 | archive-url=https://web.archive.org/web/20070322015050/http://www.ww2gyrene.org/weapons_37mm.htm | archive-date=22 March 2007 | url-status=dead}}

==External links==
{{Commons category}}
*[https://web.archive.org/web/20070808215704/http://www.fightingiron.com/FO-37mmCannon.htm Photo gallery at Fightingiron.com]
*[http://svsm.org/gallery/37mm_M3 Photo gallery at SVSM.org] {{Webarchive|url=https://web.archive.org/web/20070927005751/http://svsm.org/gallery/37mm_M3 |date=27 September 2007 }}.
*[https://books.google.com/books?id=hCcDAAAAMBAJ&pg=PA75 ''Popular Science'', April 1940, "Tanks Can Be Destroyed"]—article on early US Army concepts for tank destroyers using Gun M3 on various vehicles
*[https://books.google.com/books?id=XicDAAAAMBAJ&pg=PA83 "Little Poison", August 1942, ''Popular Science'']—excellent detailed article on the M3 antitank cannon

{{WWIIUSGuns}}

{{DEFAULTSORT:37 Mm Gun M3}}
[[Category:37 mm artillery]]
[[Category:Anti-tank guns of the United States]]
[[Category:Tank guns of the United States]]
[[Category:World War II anti-tank guns]]
[[Category:World War II weapons of China]]
[[Category:World War II tank guns]]
[[Category:Weapons and ammunition introduced in 1940]]