75 mm Gun M2 / M3 / M6 The US 75 mm gun tank gun M2 and the later M3 were the standard American tank guns of the Second World War . Besides use on the two main American medium tank s of the war the M3 Lee ( M2 or M3 gun ) and the M4 Sherman ( M3 gun ) . The lightweight M6 and M5 variants were developed to equip the Light Tank M24 and the B - 25 Mitchell bomber . Development . U . S . armored doctrine in World War II saw the tank as a deep - attack or exploitation vehicle . The tank ' s job was to pour through a breach in the enemy front line created by infantry and artillery and exploit that breach by attacking the enemy rear . The tank ' s primary armament was seen as its machine guns and sheer bulk and crushing power . The main gun was seen as a means of overcoming obstacles as the tank proceeded to attack vital enemy rear areas . For this role the tank gun required good general - purpose performance but anti - tank capability was not paramount . The tank was not supposed to engage enemy tanks . If enemy tanks were encountered in numbers , specialist Tank Destroyer units were to be called in . History . The 75mm tank gun has its origins in the famous French Canon de 75 modèle 1897 field gun of World War I fame which was also adopted by the United States and used well into World War II as the 75mm M1897 field gun . Both the tank and field guns fired the same range of 75x350R ammunition . The primary round was the M48 High Explosive . This 6 . 76 kg ( 14 . 9 lb ) round travelled at 625 m / s ( 2 , 050 ft / s ) and contained 1 . 5 pounds of TNT filling and choice of Super Quick ( SQ ) or Delay ( PD ) with 0 . 05 or 0 . 15 seconds of delay fuse . SQ was the standard setting with PD used against structures , gun positions or lightly protected vehicles . The field gun origins of the ordnance and ammunition ensured that the M2 / 3 / 6 series HE round was highly effective for its caliber . The M48 was available in 2 versions , standard or supercharge which increased the propellent charge for greater muzzle velocity ( vs . ) and range ( 2 , 300 yards greater ) . Other important rounds fired by the 75mm tank guns were the T30 Canister shot for use against troops in the open at short range . This was essentially a giant shotgun shell full of large numbers of steel balls . Canister was used primarily in the Pacific . There was also the M88 base - ejecting smoke round and the M89 White Phosphorus ( WP or " Willy Pete " ) round which proved highly effective in the Bocage fighting around Normandy . Finally there was the Armor - piercing for which 2 different rounds were provided . The first armor - piercing round was the M72 AP - T , a plain uncapped AP round whose performance dropped off as range increased due to poor aerodynamics . M72 was replaced by the 6 . 8 kg ( 15 lb ) M61 and later the improved M61A1 APC Shell . This was actually a APCBCHE - T or Armor Piercing , Capped , Ballistic - Capped , High Explosive Tracer type round which contained a tracer element so the gunner could follow the trajectory of the round to make corrections for the next shot if necessary . The aerodynamic ballistic cap acted as a windscreen and improved ballistic performance , maintained velocity , and retained penetration at longer ranges . The armor piercing cap , made of a softer metal , helped to prevent shell shatter at higher velocities and against sloped and " face - hardened " armor . Once the projectile had penetrated the target a small explosive charge at the base of the shell would detonate shattering the shell , and increasing damage inside the enemy vehicle . In practice the majority of M61 rounds were shipped without the explosive filler . M61 had a muzzle velocity of 620 m / s ( 2 , 030 ft / s ) and was credited with the ability to penetrate of armor plate at 500 yards range , which was a quite acceptable performance by the standards of 1942 . By July 1944 complaints started to pour in about the inadequate anti - tank performance of the M4 Medium tanks fitted with the 75mm M3 gun . During the breakout from Normandy American and British forces encountered the new generation of heavy German tanks and armored vehicles such as the Panther tank , Tiger I tank and Jagdpanzer IV tank destroyer in quantity for the first time . These vehicles had thick frontal armor that proved largely immune to the M61 projectiles fired by the M3 tank gun and severely tarnished the reputation of the M4 Medium tank . The western allies countered by equipping increasing numbers of M4 Medium tanks with the 76 mm gun M1 for the Americans and the Ordnance QF 17 pounder for the British . These guns offered much improved performance against tanks but because they fired High Explosive rounds that were inferior to those of the 75mm guns , the larger calibre guns never completely replaced the older models . British tanks in the early years of World War II relied on high - velocity anti - tank guns such as the Ordnance QF 2 pounder and Ordnance QF 6 pounder for their primary armament . These guns had the great disadvantage for tank use of not having a truly effective High Explosive round or not even having the option of a HE round . The British after experiencing the effectiveness of the American 75mm tank guns in the infantry support role opted to adopt the American caliber and ammunition by the expedient of boring - out the 6 pounder tank gun to make the Ordnance QF 75 mm . By 1944 this had become the standard British tank gun equipping the Cromwell tank and Churchill tank for the campaigns in northwest Europe . A version used on the early Medium Tank M3 . Longer derivative of the M2 . Equipped American and British vehicles such as the Medium Tank M4 , the later models of the Medium Tank M3 and the Churchill III / IV ( scavenged from General Sherman tanks in the North African theatre ) . US Army also experimented with mounting of the M3 on various wheeled carriages for use as anti - tank gun , but the program was cancelled due to lack of requirement . The 75 - mm Aircraft gun M4 ia a modification of the M3 gun which is found in medium tanks . It differs from the M3 gun , only in having a seat for the spline machined in the tube . it was mounted on the M6 mount . A lightweight version of the M3 with a lighter thin - walled barrel and a different recoil mechanism that was used in the B - 25H Mitchell bomber . Uses the same ammunition and has the same ballistics as the M3 . A version derived from the T13E1 for the Light Tank M24 .