76 mm gun M1
|76 mm gun M1|
An M18 Hellcat armed with a 76 mm gun
|Place of origin||United States|
|Used by||United States|
|Wars||World War II|
|Caliber||76 millimetres (3.0 in)|
The 76 mm gun M1 was an American World War II–era tank gun, which replaced the 75 mm gun on late Medium tank M4s, and was used for all 76 mm Gun Motor Carriage M18 tank destroyers. The medium-velocity 75 mm M3 L/40 gun, which armed the standard M4 Sherman, was designed as a dual purpose weapon. Although quite capable of dealing with the initially 30 mm to 50 mm thick frontal armor of German Panzer IV tanks and StuG III assault guns, the subsequent uparmoring of these AFVs to 80 mm and upgunning to the KwK 40/StuK 40 diminished the ability of the Sherman to engage at long distances, whereas the Sherman front hull could provide a very effective backstop. Due to the appearance of the Panther and Tiger tanks on the field, a higher velocity weapon was demanded.
The new 76mm gun represented a much needed increase in anti-tank performance, allowing the Sherman to engage the most common German armored vehicles like the Panzer IV and Stug III. When using HVAP (High Velocity Armor Piercing) rounds the M4 was able to engage the heavier Tiger I and Panther from ranges over 2500 yards although its performance was heavily degraded by sloped armor such as the Panther's glacis, which was immune to HVAP rounds necessitating shots to be aimed at the mantlet and turret front. The saboted 17 pounder rounds also suffered from far greater dispersion than either the American 90 mm or 76 mm guns. Years later, during the Korean War, the 76mm Shermans, using HVAP ammunition, were able to easily penetrate the Soviet T-34/85 tanks from typical combat ranges.
Design and development
It was a new gun with a breech similar to that of the 75 mm M3 Gun. It fired the same shell as the 3-inch (76 mm) M1918 gun of the 3in Gun Motor Carriage M10 tank destroyer, but from a different case. The 76 mm was developed as a lighter gun than the "3 inch". The gun received a muzzle brake and faster rifle twist during production.
While the 76 mm had less High Explosive (HE) and smoke performance than the 75 mm, the higher-velocity 76 mm gave better anti-tank performance, with firepower similar to many of the armored fighting vehicles it encountered, particularly the Panzer IV and StuG vehicles. Using the M62 APC round, the 76mm gun penetrated 109 mm (4.3 in) of armor at 1,000 m (3,300 ft), with a muzzle velocity of 792 m/s (2,600 ft/s). The HVAP round was able to penetrate 178 mm (7.0 in) at 1,000 m (3,300 ft), with a muzzle velocity of 1,036 m/s (3,400 ft/s). 
The M1 was tested on an M4 Sherman tank, it was then found that the long barrel caused balance problems. The barrel was shortened and a counterweight added to the breech to compensate, giving the M1A1. The reduction in length—by about 15 inches—reduced performance but the 76 mm was still superior to the 75 mm gun.
When the counterweight was found to be insufficient, the turret design of the T23 tank was used on the M4 chassis to carry the 76mm gun.
Wholesale introduction of the 76 mm gun was opposed due to its inferior HE round—approximately 0.9 lb (0.41 kg) of explosive to the 1.5 lb (0.68 kg) in the 75 mm round—and the muzzle blast which could create large dust clouds in dry conditions. Later production guns were given a muzzle brake to deflect the blast sideways (M1A1C).
The UK was not interested in the 76 mm gun Sherman as they had their own guns and tanks under development—although of intermediate length between the M1 and M1A1 76 mm, their Ordnance QF 17 pounder (76.2 mm) anti-tank gun used about 5.5 lb (2.5 kg) more propellant. Developed as an expediency M4 Shermans converted to use the 17pdr were known as the Sherman Firefly.
Overall, the 76mm M1 was comparable to the 17pdr. Performance was roughly equal with the 17pdr enjoying better penetration qualities, while the 76mm weapon was more accurate.
- M1: 57 caliber long gun
- M1A1: 52 caliber long version of gun with breech counterweight.
- M1A1C: fitted with muzzle brake
- M1A2: fitted with muzzle brake
With British Commonwealth designations in parentheses:
- 76 mm Gun Motor Carriage M18 (Hellcat)
- Medium Tank M4A1(76)W (Sherman IIA)
- Medium Tank M4A1(76)W HVSS (Sherman IIAY)
- Medium Tank M4A2(76)W (Sherman IIIA)
- Medium Tank M4A2(76)W HVSS (Sherman IIIAY)
- Medium Tank M4A3(76)W(Sherman IVA)
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 supported their 75 mm gunned Shermans with QF 17 pdr (76mm) equipped "Fireflies"
From 1943, at the instigation of the head of the Armored Force General Jacob Devers, US Ordnance worked on a towed anti-tank gun based on the barrel of the M1, known as "76 mm gun T2 on carriage T3". Later interest in the project declined and in 1945 the program was officially canceled.
|Ammunition||500 m||1,000 m|
|Armour-Piercing Capped (APC), US M62 or Soviet APC||109 mm, 93 mm||92 mm|
|Armour-Piercing Capped Ballistic Capped (APCBC)||98–93 mm||88 mm|
|High-Velocity Armour-Piercing (HVAP)||139 mm||127 mm|
|High-Velocity Armour-Piercing M93||146 mm||127 mm|
|High-Velocity Armour-Piercing T-4||147 mm||120 mm|
Weapons of comparable role, performance and era
- 7.5 cm KwK 40—Similar contemporary German tank gun, used on the Panzer IV F/2 and later versions
- Ordnance QF 17 pounder—British equivalent but of much higher performance than the U.S. gun
- Jentz, Thomas; Doyle, Hilary (2001). Panzerkampfwagen IV Ausf.G, H and J 1942-45. Osprey Publishing. p. 20. ISBN 1841761834.
- Moran, Nicholas. "US Firefly Part 3". World of Tanks. Retrieved 10 October 2014.
- Moran, Nicholas. "US Firefly Part 1". World of Tanks. Retrieved 24 October 2014.
- Zaloga, Steven. T-34-85 vs. M26 Pershing: Korea 1950. London: Osprey Publishing, 2010. pp. 32-33.
- M4 (76mm) Sherman Medium Tank 1943–65, p. 7.
- Steven J. Zaloga, Jim Laurier M4 (76mm) Sherman Medium Tank 1943–65 p. 4
- Steven J. Zaloga, Jim Laurier p. 4
- Steven J. Zaloga, Brian Delf. US Anti-tank Artillery 1941–45. Osprey Publishing, 2005 (New Vanguard 107). ISBN 1-84176-690-9. page 20.
- Steven J. Zaloga. and Peter Sarson (1993). Sherman Medium Tank.
- R.P. Hunnicutt (1978). Sherman: A History of the American Medium Tank.
- Bovington Tank Museum (1975). Fire and Movement.
- Harry Woodman (1991). Tank Armament in World War Two.
- TM 9-308
- SNL C-46
- SNL C-58
- SNL C-64
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