76 mm gun M1

The muzzle blast of early 76 mm guns obscured the target with smoke and dust. This could prevent the gunner from seeing where the projectile struck. The Ordnance Department initially reduced the amount of smoke by using a long primer that gave a more complete burn of the propellant before it exited the barrel.[18] The revised ammunition began to be issued for use in August 1944.[19] Muzzle brakes, that redirected the blast left and right, were tested in January 1944 and authorized in February 1944, with production starting in June 1944. Mid-production guns (M1A1C) were threaded for a muzzle brake, with the threads covered by a protector cap.[20][18] Enough muzzle brakes were produced to allow them to be released onto M4 production lines in the fall.

For those vehicles that did not have a muzzle brake, once the Armored Force began to accept M4s, it was recommended that tank commanders stand outside the tank and "spot" the strike of rounds to guide the gunner.[17]

The situation with the high-explosive shell was that the 3 inch M42 projectile for the 76 mm gun carried a filler of about 0.9 lb (0.41 kg) of explosives while the 75 mm gun M48 high explosive projectile carried 1.5 lb (0.68 kg).[21] Far more high explosive ammunition was used by tankers than armor piercing types, the ratio being about 70% HE, 20% AP and 10% smoke overall,[22] The ratio could vary by unit: From August 3 to December 31, 1944 the 13th Tank Battalion fired 55 rounds of M62 APC-T armor piercing versus 19,634 rounds of M42 high explosive.[23]

The M88 smoke round for the 76 mm provided a "curtain" of smoke.[24] The tankers found the 75 mm M64 WP (White Phosphorus) smoke projectile useful not only for providing smoke coverage but also attacking targets including enemy tanks.[25] Some units equipped with the 76 mm preferred to maintain a 75 mm armed tank on hand to provide the M88 WP projectile.[26]

It was thought that the longer and heavier 76 mm might hamper handling inside the tank's turret, slowing the rate of fire.[16] This may have been more of a concern than was warranted: on April 22, 1945, the crew of an M4 76 mm crew encountered an unidentified vehicle – which was actually a British scout car – in an ambush position, and the "76 roared twice in rapid succession". The British gunner stated that his vehicle had been destroyed, before "I could lay my hand on the trigger".[27]

It was also thought that the longer 76 mm would reduce ammunition capacity.[16] The 76 mm was first tested on the M4A1 series tank which carried 90 rounds of 75 mm ammunition,[28] while most other models carried 97 rounds of 75 mm.[29] The 76 mm cartridge reduced this to 83 rounds.[1] By late 1943, the Army had adopted the wet storage system of water containers among the rounds, to reduce fires and for the 76 mm gun this provided 71 rounds of ammunition, while the 75 mm could carry 104 rounds.[30] Storage depended on organization: The 76-mm T72 Gun Motor Carriage, designed to mount the 76-mm on the M10 GMC chassis in a T23 turret lightened for the job, carried 99 rounds (but not in wet storage).[31]

The 76 mm gun saw first use in a test batch of M18 Hellcat gun motor carriages in Italy in May 1944, under their development designation T70.[32] The moderate performance of the 76 mm gun by 1944 standards was one of three reasons the plans for M18 production were cut from 8,986 to 2,507, of which 650 were converted to unarmed utility vehicles.[33] An experiment was performed mounting the 90-mm armed M36 turret on an M18 to provide more firepower than the 76-mm.[34]

The first M4 tanks armed with 76 mm guns intended for combat were produced in January 1944.[35] Tanks equipped with the gun began arriving in Britain in April 1944.[17] The issue with muzzle blast had not been addressed and higher-level commanders had doubts about the use of, let alone need for, the new weapon.[17] The medium-velocity 75 mm M3 gun, which first armed the standard M4 Sherman, was quite capable of dealing with most of the German armored fighting vehicles met in 1942 and 1943, and had better high explosive capability and fewer issues with muzzle blast. It was not until July 1944 that a call for M4s armed with 76 mm guns was put out in France after unexpectedly high losses by US tank units and the arrival of numerous Panther tanks on the US sector of the front.[3]

Deliveries of the 76-mm armed tanks lagged such that by January 1945 they made up only 25% of the tanks in Europe. Plans were made by field units to directly replace the 75s on some tanks using a weight welded to the turret rear to balance it. A prototype was built, but the supply of ready-made tanks increased and that project ended.[36]

The 75 mm armed M4 tanks were never completely replaced during the war with some units in Europe still had about a 50/50 mix.[37] Units in Italy readily accepted the 76 mm,[38] but were never shipped as many as desired.[39] The US units in the Pacific Theater relied mainly on the 75 mm gun.[40] The 76 mm-armed M18 did see use in the Pacific late in the war.[41]

The 76 mm M1, while an improvement over the previous 75 mm, was a disappointment in its promised performance vis-à-vis the Panther tank and upgraded models of the Panzer IV Ausf. H/J in the frontal arcs. This was the case of the 76 mm M1 versus the frontal armor of these tanks only. The other arcs did not present a problem.[42] The cause of this was the M62A1 APC round issued with the gun.[42] Another issue surfaces on detailed analysis with a change induced by the problem with the M18 turret and the weight of the original 76/57 development gun. The problem is that the M18 turret was strained by the forward weight of the barrel.[42] In production, the 76mm M1 was shortened to 52 calibers to address this issue. The result was a loss in velocity and this also affected the anti-armor performance of the shell.[42] In response to the lack of performance and displeasure expressed at high levels at the lack of performance, a new shell was developed. The 76 mm M93 High-Velocity, Armor-Piercing Tracer (HVAP-T) was a large improvement being an Armor Piercing Composite Rigid shot, where the full bore, lightweight outer shell contained a slug of tungsten alloy. This improved velocity, thus penetration, but the APCR slowed faster than the AP shot or APHE shell, such that penetration dropped below that of the previous two rounds at around 1,500 yards. The American APCR data seems to indicate that US designs were superior to German and their Soviet copies in retaining their velocity to longer ranges. The US Army did not adopt the APDS shot until the middle 1950s as the British designs had significant dispersion problems from point of aim, being less accurate. In the ETO the determination of the effective range of engagements between armor fell into at or under 890 yards.[42] The shell brought the Panzer IV turret penetration to 1,850 yards. The Panther remained immune in the frontal arc. The side and rear arcs remained vulnerable out to 2,500 yards.[42] What was missing to achieve the range and penetration of 890 yards that the US Army desired goal against the Panther was 500 fps in velocity, 3400 fps vs. the required 3900 fps.[42]

The UK had developed a more effective anti-tank gun before the 76 mm gun became widely available. Although only slightly longer at 55 calibers, their Ordnance QF 17 pounder (76.2 mm) anti-tank gun had a much larger 76.2×583mmR cartridge case, which used about 5.5 lb (2.5 kg) more propellant. The anti-tank performance of the 76 mm was inferior to the British 17-pounder, more so if the latter was using APDS discarding sabot rounds, though with that ammunition the 17-pounder was less accurate than the 76 mm. The 17-pounder was also much larger and had a longer recoil than the 76 mm, which required a redesign of the turret and despite this, made the turret very cramped. The 17-pounder also had a less effective HE round. The 76 mm gunned Shermans supplied to the British were only used in Italy or by the Polish 1st Armoured Division in north-west Europe. The British and Commonwealth units in north-west Europe supported their 75 mm gunned Shermans with 17-pounder armed Sherman Fireflies.

The first 76-mm-armed Shermans started to reach Red Army units in late summer 1944. In 1945, some units were standardized to depend mostly on them, transferring their T-34s to other units. Parts of the Polish First Army also briefly used M4A2 (76 mm) tanks, borrowed from the Red Army after heavy losses in the conquest of Danzig.

By the end of 1950, more than 500 76mm gun M4A3E8 tanks were in Korea. These 76 mm-armed Shermans served well in the Korean War and, having better crew training and gun optics, had little problem piercing the armor of North Korean-manned T-34/85 tanks when firing HVAP rounds, which were amply supplied to units.[43] Some 76 mm-armed M4s [44] and M18s were distributed around the world and used by other countries post-war.[45] The 76 mm gun was sometimes replaced by a more powerful weapon in service with other nations after World War II.[6][43][45]

France delivered 76 mm-gunned Sherman tanks to Israel which used them in Operation Kadesh against Egypt in 1956 and in the 1967 Six day war, particularly in the conquest of Jerusalem. Some were still used as bulldozer tanks in the Yom Kippur War in 1973.

Some M4A3E4s, retrofitted with the M1A1 76 mm gun, as well as a few M18s, were used by various sides during the civil conflicts of former Yugoslavia during the 1990s.

Pakistan bought 547 M4A1E6(76)s during the 1950s and used them in 1965 and 1971 Indo-Pakistani Wars with neighbouring India, which also fielded Sherman tanks (M4A3E4s) as well.

Uganda purchased a few ex-Israeli M4A1(76)Ws and used them during the Idi Amin regime up until the Ugandan-Tanzanian War.

• British Ordnance QF 17 pounder
• German 7.5 cm KwK 40
• German 7.5 cm KwK 42
• Soviet 85 mm D-5T tank gun
• Soviet 100 mm D-10 tank gun