When M103 was born, many countries have switched to using main battle tanks. Only 300 M103s were ever built, and never participated in combat. By 1974, all M103 had been withdrawn from the payroll.

Joseph Stalin was a heavy tank series developed by the Soviet Union during World War II. The JS-3 began to be developed in late 1944 and could only be used on a small scale during the campaign against the Japanese army in Manchuria.

Although it was a failed design, the JS-3 also made an important contribution, forcing the US to develop a similar heavy tank, the M103. However, this tank was no better than its rival.

Beginning to be put into the payroll in 1957, the M103 was the heaviest tank the US had ever built before M1 Abram appeared. At that time, the weight of 60 tons of M103 was a huge number, when most other tanks were only 40 to 50 tons.

M-103 heavy tank review

The power of the engine was not commensurate with this weight. This made the tank move very slowly, the range was limited. In fact, when M103 was born, heavy tanks became obsolete. Many countries have switched to using main battle tanks. Only 300 M103s were ever built, and never participated in combat. By 1974, all M103 had been withdrawn from the payroll.

The introduction of the M103 heavy tank

In World War 2, the US military never had a heavy tank capable of coping with German heavy tanks like the sixty-ton Tiger, which had a bigger gun and thicker armor.

The Germans and Soviets both employed heavy tanks as breakthrough vehicles, which traded speed for heavier armament and armor to enable them to penetrate fortified lines. The British had the Churchill, a heavy but slow infantry support tank to help riflemen get through German trenches.

The United States was the exception. The only operational tank in Europe at that time, the M26 Pershing, was not even heavy enough to fulfill its missions.

Prior to World War II, a tank weighing 30 tons or more was regarded as heavy. But by the early postwar period, medium tanks had reached 45–50 tons and heavy tanks weighing over 70 tons were being considered.

After the end of the war, the Soviet heavy tanks became the new threat as these were designed to deal with the very same tanks and now were antagonized to their former allies. The IS-3 and IS-4 series have in common a strong frontal armor, sloped and 180 mm thick, and a 122 mm gun as a standard. The British had the sixty-four-ton Conqueror with a 120-millimeter gun, and even the French had the AMX-50 heavy tank.

The U.S. Army experimented after 1945 with various heavy tank designs. But spurred by growing Cold War tensions, the Army opted to push an untested design, the T-43 heavy tank armed with a 120-millimeter gun into production.

The solution was to modify the T-43 into a new vehicle called the M103, the first operational American heavy tank since the Mark VIII. Like the contemporary British Conqueror tank, the M103 was designed to counter Soviet heavy tanks, such as the later IS-series tanks or the T-10 if conflict with the Soviets broke out. Its long-ranged 120 mm cannon was designed to hit enemy tanks at extreme distances.

M103 heavy tank design

Following contemporary American design philosophy, the M103 was built with a two-piece, cast elliptic armor scheme, similar to the M48’s design. The new hull that would save weight while being optimized at all angles for maximum sloping effectiveness, saving thickness and therefore weight.

The driver was placed in the centerline of the bow, allowing better glacis designs. It featured seven road wheels per side, mounted with long-arm independent torsion bars. The 28-inch track was shoed in steel backed rubber chevron tracks.

The hull was made of welded cold RHA steel plates and partly cast. The cast “beak” was 99 to 130mm at the thickest. The driver sat in the middle, with a small rounded one-piece hatch above him, and three vision blocks covering the frontal arc. He had access to two consoles, one for the basic performances indicator and another for the engine situation. The traverse motor, along with the generator and accessory box was placed in the middle, under the main gun axis.

The turret was very large, to house the recoil mechanism and absorb its course, and cast, as the M-48 and M-60 turrets. It was also quite thick with 249mm on the mantlet, 280mm on the turret front, 76mm on the side and 38mm in on top. The configuration was not standard, with the gunner at the right hand side, the loader on the left hand side, and the commander in the middle behind the gun, with his own rotatable M11 cupola and an adjustable seat, which was placed high in the turret bustle. The commander was also responsible for the VHS one transmitter and two separate receivers housed also in the bustle. Of course, no NBC protection was offered.

M103 heavy tank engine

The Continental AV-1790 engine was placed at the rear of the tank, and produced a maximum output of 810 horsepower, fed through a General Motors CD-850-4 two-speed transmission. This allowed the 60-ton heavy tank to achieve a maximum road speed of 34 kilometres per hour and a maximum climbing gradient of 60%. The resulting performance of the tank was dismal; being severely underpowered and very fuel intensive. This presented a host of logistical problems for the vehicle, most prominently the extremely limited range of just 130 km. Though this was partially corrected with the introduction of the AV-1790-2 diesel unit, it would remain cumbersome and fuel-thirsty for the majority of its service life.

M103 heavy tank armament

The M103 was designed to mount the 120 mm M58 gun. Using standard Armor-Piercing Ballistic Cap Tracer Rounds. In its configuration, this gun was able to score hits at 2,500 to 3,500 m with good accuracy. The commander could select from 34 rounds of either M358 Armor-Piercing Ballistic Cap Tracer Rounds or M469 HEAT shells, mounted at the rear of the turret and in the hull. With both loaders, the maximum firing rate of the gun was five rounds per minute, owing to the design of the two-piece ammunition. Using the electrohydraulic turret traverse, the gunner could turn the turret at 18 degrees per second, with 15 degrees of elevation and 8 degrees of gun depression.

Secondary armament comprised a twin coaxial mount for cal.30 with 5250 rounds in store, the usual M2 cal.50 on the roof, at the extreme rear of the turret.

M103 heavy tank served in the United States Army

The US M103 Heavy Tank entered service in the US Army in 1957. 300 were built, 220 vehicles were standardized after modifications for the USMC as the M103A1, and the US Army requested 72 tanks from the USMC stocks, that were sent in Europe and attached to the 899th heavy tank battalion of the 7th US Army.

Interestingly, the Germans had found that while they didn’t lose many heavy tanks in combat, they abandoned a lot more during retreats: towing a broken down seventy-ton King Tiger from the battlefield was no easy task. Faced with the prospect of an overwhelming Soviet armored assault, the Seventh Army had every reason to want a heavy tank that could survive a retreat as well as an advance.

Nonetheless, the M103 still suffered from traditional heavy tank problems. It was found that the engine was underpowered, requiring replacement of engines and transmissions after average mileage distances of only about 500. The ammunition stowage was not convenient, repeated firing of AP ammunition caused excess chamber erosion, tracks were easily thrown, crew safety, comfort and ability to function were impaired by poor interior arrangement.

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But even with its flaws, the M103 was still useful. Although it was felt that the tank was sluggish, it could do the job intended. During the service in Europe, the heavy gun tanks were well liked by their crews. The troops recognized that the powerful 120mm gun was far superior in penetration performance lo the 90mm cannon of the medium tanks.


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