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M103
M103A1
M103A2


120mm Gun Tank M1031-6
M103: General
Date of first acceptance May 1953 Total acceptances 300
Manufacturer Chrysler Corp. Crew
5 men:
  • Commander in turret rear
  • Gunner in turret right rear
  • Two loaders in turret rear
  • Driver in hull center front
M103: Dimensions
Combat weight ~125,000lbs
~56,700kg
Height over cupola MG 140.1"
355.9cm
Length without gun 275.3"
699.2cm
Gun overhang forward 173.3"
440.2cm
Width over tracks 143.0"
363.2cm
Tread 115.0"
292.1cm
Ground clearance 15.4"
39.1cm
Fire height ~82"
~210cm
Turret ring diameter 85.0"
216cm
Ground pressure, zero penetration 12.9psi
.908kg/cm²
M103: Armament
Type Mount Ammunition Traverse Max traverse rate Elevation Max elevation rate
120mm Gun M58 M89 in turret 33 rounds 360°
(manual and electric-hydraulic)
18°/sec +15° to -8°
(manual and electric-hydraulic)
4°/sec
.50cal M2HB MG Remote control mount on M4 cupola 900 rounds 360° -- -- --
Two .30cal M1919A4E1 MGs Coaxial to 120mm gun 8150 rounds 360°
(manual and electric-hydraulic)
18°/sec +15° to -8°
(manual and electric-hydraulic)
4°/sec
Rangefinder
Stereoscopic M14
Night vision
Infrared periscope M24 for driver
M103: Armor
Assembly
Welding
Hull
Rolled and cast homogeneous steel
Location Thickness Angle from vertical
Upper front 5.0"
13cm
60°
Lower front 4.5"
11cm
50°
Upper sides 2.0" equivalent
5.1cm equivalent
40°
Lower sides 1.75" equivalent
4.45cm equivalent
30°
Upper rear 1.5"
3.8cm
30°
Lower rear 1.0"
2.5cm
60°
Top 1.0"
2.5cm
90°
Front floor 1.5"
3.8cm
90°
Rear floor 1.25"
3.18cm
90°
Turret
Cast homogeneous steel
Location Thickness Angle from vertical
Gun shield 10" to 4"
25cm to 10cm
0° to 45°
Front 5.0"
13cm
50°
Sides 5.38" to 2.75"
13.7cm to 6.99cm
20° to 40°
Rear 2.0"
5.1cm
40°
Top 1.5"
3.8cm
85° to 90°
M103: Automotive
Engine Continental AV-1790-5B, -7, -7B, or -7C; 12 cylinder, 4 cycle, 90° vee gasoline
Horsepower Net: 690@2800rpm
Gross: 810@2800rpm
Torque Net: 1410 ft-lb@2000rpm
Gross: 1600@2200rpm
Fuel capacity 280gal
710L
Transmission General Motors CD-850-4A or -4B, 2 ranges forward, 1 reverse
Steering Mechanical, steering wheel
Brakes Multiple disc
M103: Suspension
Type Road wheels Track return rollers
Torsion bar 7 independently sprung dual/track 6 dual/track
Drive sprockets Idlers Shock absorbers
11-tooth rear drive Dual compensating at front of track On first 3 and last 2 road wheels/track
M103: Track
T96
Center guide, double pin, rubber backed steel
Width 28"
71cm
Pitch 6.94"
17.6cm
Shoes/track 82 or 81 Ground contact length 173.4"
440.3cm
T97
Center guide, double pin, rubber chevron
Width 28"
71cm
Pitch 6.94"
17.6cm
Shoes/track 82 or 81 Ground contact length 173.4"
440.4cm
T97E1
Center guide, double pin, rubber chevron
Width 28"
71cm
Pitch 6.94"
17.6cm
Shoes/track 82 or 81 Ground contact length 173.4"
440.4cm
T97E2
Center guide, double pin, rubber chevron
Width 28"
71cm
Pitch 6.94"
17.6cm
Shoes/track 82 or 81 Ground contact length 173.4"
440.4cm
M103: Performance
Max level road speed 21mph sustained
34kph sustained
Max trench 90"
230cm
Max grade 60% Max vertical obstacle 36"
91cm
Min turning diameter Pivot Max fording depth 48"
120cm
Cruising range ~80mi
~130km


The M103 heavy tank was intended to take on the Soviet IS-3 and T-10 series of heavy tanks. The first production M103s were not considered fit for service and were placed in storage until their faults could be rectified. Not until 98 modifications were applied to the vehicles, including fixes to ammunition, turret controls, and sighting and gun controls, were the tanks finally accepted and standardized in April 1956. The first 60 vehicles featured a small driver's hatch, while later tanks came equipped with a larger hatch. Not all of the small hatches were able to be fitted with the mount for the M24 infrared periscope. The commander and gunner sat in the bustle of the very large turret, and two loaders were required to feed the separate projectile and propellant to the potent 120mm gun. The commander's .50cal machine gun could be fired from under armor, but the commander had to expose himself to reload the weapon. The coaxial machine guns were placed on on each side of the 120mm gun.

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120mm Gun Tank M103A11-6
M103A1: General
Total acceptances 219 Crew
5 men:
  • Commander in turret rear
  • Gunner in turret right front
  • Two loaders in turret rear
  • Driver in hull center front
M103A1: Dimensions
Combat weight ~125,000lbs
~56,700kg
Height over cupola MG 140.1"
355.9cm
Length without gun 275.3"
699.2cm
Gun overhang forward 173.3"
440.2cm
Width over tracks 143.0"
363.2cm
Tread 115.0"
292.1cm
Ground clearance 15.4"
39.1cm
Fire height ~82"
~210cm
Turret ring diameter 85.0"
216cm
Ground pressure, zero penetration 12.9psi
.908kg/cm²
M103A1: Armament
Type Mount Ammunition Traverse Max traverse rate Elevation Max elevation rate
120mm Gun M58 M89A1 in turret 38 rounds 360°
(manual and amplidyne)
21°/sec +15° to -8°
(manual and amplidyne)
4°/sec
.50cal M2HB MG Flexible mount on M11 cupola 1000 rounds 360°
(Manual)
-- Manual --
.30cal M37 MG Coaxial to 120mm gun 5250 rounds 360°
(manual and amplidyne)
21°/sec +15° to -8°
(manual and amplidyne)
4°/sec
Rangefinder
Stereoscopic M15
Night vision
Infrared periscope M24 for driver
M103A1: Armor
Assembly
Welding
Hull
Rolled and cast homogeneous steel
Location Thickness Angle from vertical
Upper front 5.0"
13cm
60°
Lower front 4.5"
11cm
50°
Upper sides 2.0" equivalent
5.1cm equivalent
40°
Lower sides 1.75" equivalent
4.45cm equivalent
30°
Upper rear 1.5"
3.8cm
30°
Lower rear 1.0"
2.5cm
60°
Top 1.0"
2.5cm
90°
Front floor 1.5"
3.8cm
90°
Rear floor 1.25"
3.18cm
90°
Turret
Cast homogeneous steel
Location Thickness Angle from vertical
Gun shield 10" to 4"
25cm to 10cm
0° to 45°
Front 5.0"
13cm
50°
Sides 5.38" to 2.75"
13.7cm to 6.99cm
20° to 40°
Rear 2.0"
5.1cm
40°
Top 1.5"
3.8cm
85° to 90°
M103A1: Automotive
Engine Continental AV-1790-5B, -7, -7B, or -7C; 12 cylinder, 4 cycle, 90° vee gasoline
Horsepower Net: 690@2800rpm
Gross: 810@2800rpm
Torque Net: 1410 ft-lb@2000rpm
Gross: 1600@2200rpm
Fuel capacity 280gal
710L
Transmission General Motors CD-850-4A or -4B, 2 ranges forward, 1 reverse
Steering Mechanical, steering wheel
Brakes Multiple disc
M103A1: Suspension
Type Road wheels Track return rollers
Torsion bar 7 independently sprung dual/track 6 dual/track
Drive sprockets Idlers Shock absorbers
11-tooth rear drive Dual compensating at front of track On first 3 and last 2 road wheels/track
M103A1: Track
T96
Center guide, double pin, rubber backed steel
Width 28"
71cm
Pitch 6.94"
17.6cm
Shoes/track 82 or 81 Ground contact length 173.4"
440.3cm
T97
Center guide, double pin, rubber chevron
Width 28"
71cm
Pitch 6.94"
17.6cm
Shoes/track 82 or 81 Ground contact length 173.4"
440.4cm
T97E1
Center guide, double pin, rubber chevron
Width 28"
71cm
Pitch 6.94"
17.6cm
Shoes/track 82 or 81 Ground contact length 173.4"
440.4cm
T97E2
Center guide, double pin, rubber chevron
Width 28"
71cm
Pitch 6.94"
17.6cm
Shoes/track 82 or 81 Ground contact length 173.4"
440.4cm
M103A1: Performance
Max level road speed 21mph sustained
34kph sustained
Max trench 90"
230cm
Max grade 60% Max vertical obstacle 36"
91cm
Min turning diameter Pivot Max fording depth 48"
120cm
Cruising range ~80mi
~130km


M103A1 introduced a turret basket into the series, eliminating the need for the loaders to dance around the tank whenever the turret traversed. The gunner was moved about four feet (120cm) forward, and he was provided with a new telescope as a secondary sight, which replaced the right-hand coaxial machine gun. The tank's rangefinder was coupled with the M14 ballistic computer. The turret traverse was changed to an electric amplidyne system, and the commander's cupola was modified, eliminating the geared traverse, and as well the ability to fire the .50cal machine gun from within the vehicle. The front of the 120mm gun's blast deflector was eliminated due to erosion around the deflector holes.

The improvements made to the tanks finally allowed the design to meet Continental Army Command standards, however by the time the new features were ready to be rolled out the Army had relegated the M103 to standby status and did not plan further production. The Marine Corps, however, approved conversion of 219 of their M103s to M103A1 standard in June 1957. The Marine program was completed by July 1959, and in February of that year the Marines loaned the Army 72 of their M103A1s.


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120mm Gun Tank M103A21-6
M103A2: General
Date of first acceptance December 1962 Total acceptances 208
Manufacturer Red River Army Depot Crew
5 men:
  • Commander in turret rear
  • Gunner in turret right front
  • Two loaders in turret rear
  • Driver in hull center front
M103A2: Dimensions
Combat weight ~128,000lbs
~58,100kg
Height over cupola MG 140.1"
355.9cm
Length without gun 275.3"
699.2cm
Gun overhang forward 166.9"
423.9cm
Width over tracks 143.0"
363.2cm
Tread 115.0"
292.1cm
Ground clearance 15.4"
39.1cm
Fire height ~82"
~210cm
Turret ring diameter 85.0"
216cm
Ground pressure, zero penetration 13.2psi
.929kg/cm²
M103A2: Armament
Type Mount Ammunition Traverse Max traverse rate Elevation Max elevation rate
120mm Gun M58 M89A1 in turret 38 rounds 360°
(manual and amplidyne)
21°/sec +15° to -8°
(manual and amplidyne)
4°/sec
.50cal M2HB MG Flexible mount on M11 cupola 1000 rounds 360°
(Manual)
-- Manual --
.30cal M37 MG Coaxial to 120mm gun 5250 rounds 360°
(manual and amplidyne)
21°/sec +15° to -8°
(manual and amplidyne)
4°/sec
Rangefinder
Coincidence M24
Night vision
Infrared periscope M24 for driver
M103A2: Armor
Assembly
Welding
Hull
Rolled and cast homogeneous steel
Location Thickness Angle from vertical
Upper front 5.0"
13cm
60°
Lower front 4.5"
11cm
50°
Upper sides 2.0" equivalent
5.1cm equivalent
40°
Lower sides 1.75" equivalent
4.45cm equivalent
30°
Upper rear 1.5"
3.8cm
30°
Lower rear 1.0"
2.5cm
60°
Top 1.0"
2.5cm
90°
Front floor 1.5"
3.8cm
90°
Rear floor 1.25"
3.18cm
90°
Turret
Cast homogeneous steel
Location Thickness Angle from vertical
Gun shield 10" to 4"
25cm to 10cm
0° to 45°
Front 5.0"
13cm
50°
Sides 5.38" to 2.75"
13.7cm to 6.99cm
20° to 40°
Rear 2.0"
5.1cm
40°
Top 1.5"
3.8cm
85° to 90°
M103A2: Automotive
Engine Continental AVDS-1790-2A 12 cylinder, 4 cycle, 90° vee supercharged diesel
Horsepower Net: 643@2400rpm
Gross: 750@2400rpm
Torque Net: 1575 ft-lb@1750rpm
Gross: 1710@1800rpm
Fuel capacity 440gal
1670L
Transmission General Motors CD-850-6 or -6A, 2 ranges forward, 1 reverse
Steering Mechanical, steering wheel
Brakes Multiple disc
M103A2: Suspension
Type Road wheels Track return rollers
Torsion bar 7 independently sprung dual/track 6 dual/track
Drive sprockets Idlers Shock absorbers
11-tooth rear drive Dual compensating at front of track On first 3 and last 2 road wheels/track
M103A2: Track
T107
Center guide, double pin, rubber chevron
Width 28"
71cm
Pitch 7.09"
18.0cm
Shoes/track 81 Ground contact length 173.4"
440.3cm
M103A2: Performance
Max level road speed 23mph sustained
37kph sustained
Max trench 102"
259cm
Max grade 60% Max vertical obstacle 36"
91cm
Min turning diameter Pivot Max fording depth 48"
120cm
Cruising range ~300mi
~480km


M103A2 development was initiated by the Marine Corps in June 1961, and the tank was powered by the diesel engine also seen on the M60 and M48A3 tanks. Like these tanks, the M103A2's rear hull was changed to incorporated an infrared-insulated rear deck, and the engine exhaust was routed through grille doors in the hull rear. The new rear hull necessitated a new gun travel lock, which replaced the tripod arrangement with a travel lock mounted on the extreme rear of the top deck. The diesel's better fuel economy and an increased load of fuel greatly increased the tank's range. The M103A2's fire control system incorporated metric units, a more user-friendly coincidence rangefinder was installed, and a xenon searchlight could be mounted. The three pilot M103A2s had the second and fifth track return rollers removed from each side.

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References

  1. Hunnicutt, R.P. Firepower: A History of the American Heavy Tank. Navato, CA: Presidio Press, 1988.

  2. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.

  3. Estes, Kenneth W. Marines Under Armor. Annapolis, MD: Naval Institute Press, 2000.

  4. ---. "The Marine Corps's Struggle with Armor Doctrine during the Cold War (1945-70)." Camp Colt to Desert Storm: The History of U.S. Armored Forces. Eds. George F. Hofmann, Donn A. Starry. USA: University Press of Kentucky, 1999.

  5. Miller, David. The Illustrated Directory of Tanks of the World. Osceola, WI: MBI Publishing Co., 2000.

  6. Hogg, Ian V. The Greenhill Armoured Fighting Vehicles Data Book. London: Greenhill Books, 2000.



Last updated 27 Feb 2012.

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© Copyright 2001-12 Chris Conners