United States' M3, M3A1 Gun Motor Carriage:

Photos

M3 Gun Motor Carriage Aberdeen Tank Museum

Design

The British and American armies wanted a half track that would carry an anti tank gun.⁴ An M3 half track was adapted in 1941 by adding M1897A 75 mm gun.⁴

Alterations

The M3 75 mm Gun Motor Carriage had the fuel tanks moved towards the rear to make room for the 75 mm gun.⁴

Main Armament

The 75 mm M1897A was a copy of a French gun used in World War I.⁴

Initially the gun shield was the full height version, but this caused the silhouette to be too high, so it was reduced.⁴

Gun would fire at velocity of 2,000 ft/sec³ and penetrate 3 inches at 1,000 yards. Detachable canvas top. The APC shell weighed 18 lbs.³

Prototype

Production

Standardized in November 1941. It was classified as Limited Standard in March 1944, and declared obsolete in September 1944.

• M3:
  • Production: 1941³
  • Manufacturer: Autocar³
• M3, M3A1: 2,200¹
• M3A1: 324
• Total: 2,202⁴
  • Converted by: Autocar⁴

Variants

• M3: Used M2A3 gun mount.⁴
• M3A1: Used M2A2 gun mount.⁴
• 75 mm SP Autocar: Name used by British.⁴
• T-12 GMC: The Marines converted M3s by adding a 75 mm pack howitzer or the 105 mm howitzer. Had crew of 5 and was used extensively in the Pacific.
• T-19: An order was placed in March 1942.¹ Declared obsolete in 1944.¹ Had 105 mm gun installed.¹ Used in North Africa.¹
• 75 mm Howitzer Motor Carriage T30: Converted M3 half tracks and 500 built with 75 mm Howitzer M1A1. Elevation of 25° and traverse 21° left and 23° right. Used by HQ companies of medium tank battalions until replaced by M8 in 1943.

Usage

First vehicles sent to Philippines in late 1941.¹ There were 50 that were shipped.⁴

Used in Tunisia.

Used by British in Italy.

Specifications

	M3 Gun Motor Carriages	M3 Gun Motor Carriages, M3A1 Gun Motor Carriages	T-19 Gun Motor Carriages
Crew	Commander, driver, gunner, gun 53,4	Commander, driver, gun crew (3) 61	51
Physical Characteristics
Weight	18,085 lb3 10 tons4 10,160 kg4	20,000 lb 8.9 tons1 9,071 kg1	9.2 tons1 9,298 kg1
Length w/gun	20' 3"4, 20' 5.5"3 6.14 m4	20' 5.5", 20' 3"1 6.2 m1	20' 3"1 6.2 m1
Length w/o gun
Height	7' 5"4, 8' 2 5/8"3 2.26 m4	8' 2 5/8", 7' 5"1 2.28 m1	7' 5"1 2.28 m1
Width	7' 1"3, 7' 3"4 2.22 m4	7' 1", 7' 4"1 2.24 m1	7' 4"1 2.24 m1
Width over tracks
Ground clearance	11 3/16"3	11 3/16"
Ground contact length	46.75"3	3' 10.75"
Ground pressure	12 psi3
Turret ring diameter
Armament
Main	2.95" M1897 A44 75 mm M1897A43,4	75 mm M1897A4 gun1	105 mm M2 howitzer1
Secondary
MG	0.3" MG4 7.62 mm MG4
Side arms		M1903 .30 Rifle 4: M1 .30 carbines Grenades
Quantity
Main	593,4	591	81
Secondary
MG
Side arms		Grenades: 22
Armor Thickness (mm)	0.5"4 12.7 mm4	131	131
Hull Front, Upper	0.5"@0°3	6
Hull Front, Lower		6
Hull Sides, Upper	0.25"@0°3	6
Hull Sides, Lower		6
Hull Rear	0.25"@0°3	6
Hull Top		6
Hull Bottom		6
Shield Front	0.625"@0°3
Shield Sides	0.25"@0°3
Shield Rear
Shield Top
Engine (Make / Model)	White 160 AX3,4	White 160 AX1	White 160 AX1
Bore / stroke
Cooling	Water3
Cylinders	63
Capacity
Net HP	1284, 1473
Power to weight ratio
Compression ratio
Transmission (Type)	Dual range synchromesh3 8 forward, 2 reverse3
Steering	Cam and lever, front wheels only3
Steering ratio
Starter
Electrical system
Ignition
Fuel (Type)	Gasoline3, Gasoline4
Octane
Quantity	60 gallons3	60 gallons
Road consumption	3.5 mpg3
Cross country consumption
Performance
Traverse	19° left, 21° right3 Hand3
Speed - Road	45 mph3,4 64 kph4	45 mph1 72 kph1	45 mph1 72 kph1
Speed - Cross Country
Range - Road	200 miles3,4 280 km4	200 miles, 180 miles1 290 km1	180 miles1 290 km1
Range - Cross Country
Turning radius	30'3	30'
Elevation limits	-10° to +29°3
Fording depth	2' 8"3	2' 8"
Trench crossing
Vertical obstacle	1'3	1'
Climbing ability	30° slope3
Suspension (Type)	Front wheels: Semi elliptic spring3 Rear tracks: Vertical volute springing3
Wheels each side	Articulated dual wheel, four wheel bogies3	4
Return rollers each side	13	1
Tracks (Type)	Endless band3
Length
Width	1'3
Diameter
Number of links
Pitch	4"3
Tire tread
Track centers/tread	63 3/16"3, 64.5"3
Tire size	8.25 x 203
Wheel base	135.5"3