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United States' M7 Howitzer Motor Carriage:

M7 Howitzer Motor Carriage, Priest: Aberdeen Tank Museum	M7 Howitzer Motor Carriage, Priest: Royal Armored Corps Tank Museum	M7 Howitzer Motor Carriage, Priest: In North Africa: U.S. Army in World War II - Pictorial Record, 1951	M7 Howitzer Motor Carriage, Priest: Changing worn out barrel:
M7 Howitzer Motor Carriage, Priest: Training in late 1942:	M7 Howitzer Motor Carriage, Priest:	M7 Howitzer Motor Carriage, Priest:	M7 Howitzer Motor Carriage, Priest: US Ordnance Dept.⁷
M7 Howitzer Motor Carriage, Priest:	M7 Howitzer Motor Carriage, Priest:	M7B1 Howitzer Motor Carriage, Priest: Patton Museum in Ft Knox, Kentucky Chris Bobo	M7 Howitzer Motor Carriage, Priest: US Ordnance Dept.⁷
M7 Howitzer Motor Carriage, Priest. From the M7 manual: Mark Holloway	M7 Howitzer Motor Carriage, Priest. From the M7 manual: Mark Holloway	M7 Howitzer Motor Carriage, Priest. From the M7 manual: Mark Holloway	M7 Howitzer Motor Carriage, Priest. From the M7 manual: Mark Holloway
M7 Howitzer Motor Carriage, Priest. From the M7 manual: Mark Holloway	M7 Howitzer Motor Carriage, Priest, at Fort Benning in 1943: Life Magazine (Mark Holloway)	M7 Howitzer Motor Carriage, Priest in Normandy, France: Life Magazine (Mark Holloway)
M37 Aberdeen Tank Museum	M37	M37	M37

Based on experience with mounting 105 mm howitzers on half-tracks the US Army wanted a fully tracked version. Used a modified M3 Medium or M4 Medium tank chassis. Upper hull was modified to hold a 105 mm howitzer in the front. A drum-like cupola was added on the right side to hold a .50 cal MG.

Was declared Substitute Standard in January 1945.

Production models had modified shields and a cupola for the AA MG. The 105 mm gun could fire a 33 lb HE shell at a velocity of 1,550 ft/sec, and a range of 11,500 yards.⁶

First used by the US Army in 1942.¹

The Marines would use them in an armored personnel carrier roll. It could carry up to 13 marines up to the front lines. The Marines used them extensively on Okinawa.

Used M3 Medium chassis.¹ Late models had M4 type bogies with trailing return rollers.¹ Some had cast one part nose.¹ American Locomotive produced vehicles. The upper parts of the side and rear armor are hinged and held in place by locked pins. There were grip handles on the outside of the armor that were used as ladders.

The driver had vision through a removable windshield and a protoscope.

M37 Howitzer Motor Carriage:

Some felt that the M7 was too heavy so a M24 chassis was used.¹ Standardized in November 1944.¹ 448 were ordered.¹

Had drive sprocket in rear with individual torsion bar suspension. Had larger working space and storage space for ammunition than M7.¹ It was powered by twin Cadillac engines. It had Hydra-Matic transmissions.

The 105 mm gun fired a 33 lb HE shell at a range of 12,200 yards.⁶

Prototypes

Two prototypes were built and designated T32.¹ Had an open superstructure with a M1A2 105 mm howitzer installed to the right of the center. It was accepted and standardized as the M7 HMC in February 1942.

Production

Production started in April 1942.¹

M7 Howitzer Motor Carriage:
- 1942: 2,028⁷
  - Manufacturer: American Locomotive⁷
- 1943: 786⁷
  - Manufacturer: American Locomotive⁷
- 1944: 700⁷
  - Manufacturer: American Locomotive⁷, Pressed Steel Car⁷
- Manufacturer: American Locomotive Co^6,7, Federal Machine & Welder Co.⁶, Pressed Steel Car Co.^6,7
M7B1 Howitzer Motor Carriage:
- March 1944 - February 1945: 826
- 1944: 464⁷
- 1945: 162⁷
- Manufacturer; Pressed Steel Car⁷
M7B2 Howitzer Motor Carriage:
- 1945: 127⁷
- Manufacturer: Federal Machine and Welder⁷
M37 Howitzer Motor Carriage: 316^1,5
- Manufacturer: Cadillac (Detroit), Massey-Harris (Milwaukee)⁵, Cadillac⁶

Variants

T32 Howitzer Motor Carriage: Prototype.⁷
M7 Howitzer Motor Carriage: Used M3 Medium Tank chassis.⁷
M7B1 Howitzer Motor Carriage: Standardized in September 1943. Declared Substitute Standard in January 1945. Used chassis of M4A3.⁷ Cast nose. Pressed Steel produced vehicles. There were hinged plates on the side to protect the tips of the ammunition (stored vertically) from being hit by arms fire.¹Late models had lower hull made out of soft steel because of economy measures.¹ Federal Welder built 127 of both types.
M37 Howitzer Motor Carriage:

Usage

British Service:

Initially ordered 2,500 and this was later increased by 3,000.¹ The MG gun position reminded the British soldiers of a church pulpit and was called the "Priest."^1,6

Priest: In September 1942, 90 M7s were sent to 8th Army and was available for Battle of Alamein.^1,7 Were used in Normandy but were soon replaced by Sextons. Could have a No. 19 wireless radio installed if 24 rounds of ammunition were removed.
Used by the 5th Royal Horse Artillery at the Battle of Alamein.⁶
Priest Kangaroo: 102 were converted from October 1944 - April 1945. Carried 20 infantrymen plus crew of 2.
Priest OP: Removed gun and added communications gear.

	M7 Howitzer Motor Carriage, Priest	M7B1 Howitzer Motor Carriage	M37 Howitzer Motor Carriage
Crew	Commander, driver, gun crew (5).^2,7 5³ 7^1,2,6,7	Commander, driver, gun crew (5).² 7²	Commander, driver, gun crew (5) 7^1,6
Physical Characteristics
Weight	50,634 lb^2,3,7 22.6 tons¹, 28.5 tons⁶ 22,997 kg^1,3	50,000 lb^2,7	40,000 lb 20.5 tons¹, 23 ton⁶ 20,865 kg¹
Length w/gun	19' 9"^1,2,3,7, 20.4'⁶ 6 m¹, 6.02 m³	20' 3.75"^2,7	18'^1,6, 18' 2" 5.48 m¹
Length w/o gun
Height	8' 4"^1,2,3,7, 9.7'⁶ 2.5 m¹, 2.54 m³	8' 4"²	7' 4", 7.9'⁶, 7' 11"¹ 2.41 m¹
Width	9' 5.25"^2,3,7, 9' 6"^1,6 2.88 m³, 2.9 m¹	9' 5.25"²	9' 8"¹, 9.8'⁶, 9' 11" 2.99 m¹
Width over tracks
Ground clearance	1' 5", 17.1"⁶	1' 5"	1' 5", 18.4"⁶
Ground contact length	147"⁶	147"	123"⁶, 124"
Ground pressure	10.4 psi⁶	10.4 psi	10.1 psi, 11.7 psi⁶
Turret ring diameter
Armament
Main	105 mm howitzer³ 105 mm M1 howitzer¹ 105 mm M1A2^2,7 105 mm howitzer M2A1, L/24⁶	105 mm howitzer M1A2, M2, or M2A1²	105 mm M4 in M5 mount, 105 mm M4 howitzer¹ 105 mm howitzer M4⁶
OR	105 mm M2 howitzer^1,2,7
OR	105 mm M2A1 howitzer^2,7
Secondary
MG	12.7 mm (.50 cal)³		12.7 mm (.50 cal) MG .50 cal M2 MG⁶
MG - antiaircraft	.50 cal MG^2,7 .50 cal M2 MG⁶	.50 cal MG²
Side arms	3: .45 Submachine guns	3: .45 Submachine guns	.45 Submachine gun, 6: .30 carbines Grenades
Quantity
Main	69^2,6,7	69²	90, 126⁶
Secondary
MG	300^2,6,7	300²	500, 990⁶
Side arms	.45: 1,620	.45: 1,620	.45: 600 Grenades: 8
Armor Thickness (mm)	12^2,7, 62^2,7 (Actual thickness of armor at horizontal) Front: 1"⁶ Side: 0.5"⁶	12², 62² (Actual thickness of armor at horizontal)	(Actual thickness of armor at horizontal) Front: 0.5"⁶ Side: 0.5"⁶
Hull Front, Upper	0.5" (0.5")	0.5" (0.5")	0.5" (1.25")
Hull Front, Lower	2-4.25" (2-4.5")	2-4.25" (2-4.5")	0.5" (7/8")
Hull Sides, Upper	0.5" (0.5")	0.5" (0.5")	0.5" (0.5")
Hull Sides, Lower	1.5" (1.5")	1.5" (1.5")	0.5" (0.5")
Hull Rear	0.5-1.5" (0.5-1.5")	0.5-1.5" (0.5-1.5")	0.5" (7/8")
Hull Top
Hull Bottom	0.5-1" (0.5"-1")	0.5-1" (0.5"-1")	3/8-0.5" (3/8-0.5")
Turret Front			Gun mount shield: 0.5" (0.5")
Turret Sides
Turret Rear
Turret Top
Engine (Make / Model)	Continental R-975 C1^1,6 Continental R-975^2,7 Continental³	Ford GAA V8^1,2,7	2: Cadillac 44T24¹ 2: Cadillac⁶
Bore / stroke	4 cycles⁶
Cooling	Air^6,7		Water⁶
Cylinders	9³, R-9⁶		V-8⁶
Capacity
Net HP	350@2,400 rpm⁶, 375³		110@3,400 rpm⁶
Power to weight ratio
Compression ratio
Transmission (Type)	Synchromesh⁶ 5 forward 1 reverse⁶	5 forward 1 reverse	Hydramatic⁶, Hydra-Matic 2 forward, 1 reverse⁶ 8 forward 4 reverse
Steering	Controlled differential⁶		Controlled differential⁶
Steering ratio
Starter	Electric⁶		Electric⁶
Electrical steering	24-volt⁶		24-volt⁶
Ignition	Magneto⁶		Distributor⁶
Fuel (Type)	Gasoline⁶		Gasoline⁶
Octane
Quantity	179 gallons⁶	179 gallons	110 gallons⁶, 115 gallons
Road consumption
Cross country consumption	0.5 mpg⁶		0.9 mpg⁶
Performance
Traverse	12.25° left and 25.5° right⁶ 15° left and 30° right^1,2,7	15° left and 30° right²	22.5° each⁶, 45° up¹
Max speed	24 mph^1,6, 25 mph, 26 mph^3,7 39 kph¹, 41.8 kph³	25 mph	30 mph¹, 35 mph⁶ 48 kph¹
Cross country speed	15 mph^2,7	15 mph²	5-25 mph⁶, 15 mph
Road radius	85 - 125 miles⁷, 120 miles¹, 125 miles³ 193 km¹, 201 km³		100 miles¹, 160 km¹ 85-125 miles
Cross country radius	85 miles⁶		100 miles⁶
Turning radius	62'	62'	40'
Elevation limits	+35° to -5°^1,2,6,7	+35° to -5°²	+45° to -10°⁶
Fording depth	4'^2,3,6,7 1.219 m³	3'^2,7	42"⁶
Trench crossing	7' 6"^2,6,7	7' 6"²	7', 9'⁶
Vertical obstacle	2'^2,6	2'²	36"⁶, 3' 8"
Climbing ability	31° (60%) slope⁶		31° (60%) slope⁶
Suspension (Type)	Vertical volute^2,6,7	Vertical volute.²	Vertical volute Torsion bar⁶
Wheels each side	6, 3 bogies - 2 wheels each⁶	6	5⁶, 6
Return rollers each side	3⁶	3	3, 4⁶
Tracks (Type)	Dry pin, double pin per shoe, rubber bushed cleat⁶		Steel block, with center guide, rubber bushings⁶
Length
Width	1' 4.5"^2,7, 16.6"⁶	1' 4.5"²	16"⁶, 1' 4.5"
Diameter
Number of links	79⁶		80⁶
Pitch	6"⁶		5.5"⁶
Tires
Track centers/tread	6.9'⁶, 6' 11"^2,7	6' 11"²	6' 11", 8'⁶

Sources:

The Encyclopedia of Tanks and Armored Fighting Vehicles - The Comprehensive Guide to Over 900 Armored Fighting Vehicles From 1915 to the Present Day, General Editor: Christopher F. Foss, 2002
British and American Tanks of World War Two, The Complete Illustrated History of British, American, and Commonwealth Tanks 1933-1945, Peter Chamberlain and Chris Ellis, 1969
The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
-
Tanks of World War II, Duncan Crow, 1979
Tank Data, Aberdeen Proving Grounds Series, 1968?
Profile: AFV Weapons 26: Hellcat, Long Tom and Priest and Complete Check List of all U.S. World War II Self-Propelled Weapons, Colonel Robert J. Icks, 1971