Image: M21 MMC (US Army Photo)
YearAugust 1941
Vehicle Type[@type]
Origin & Designer[@designer]
Numbers Produced572
Crew6 (Commander, two Gunners, Two Loaders & Driver)
Main Armament1 x 81mm M1 Mortar (Rear Facing)
Main Armament[@sponson_traverse]
Elevation-7° to +60°
Turret Traverse60° (Manual)
Gun Traverse[@gun_traverse]
Gun Mount[@gun_mounts]
Maximum Range[@maximum_range]
Armour Penetration[@armour_penetration]
Gun Sight6.10m
Secondary Armament1 x .30 cal M1919A4 Machine Gun
Smoke Discharger[@smoke_discharger]
Ammunition Carried112 x 81mm + 2000 x .30 cal
Combat Weight7.970 kg
Ground Clearance0.28m
Fording Depth0.81m
Trench Crossing0.76m
Obstacle Clearance0.30m
Climbing Ability31°
ArmourUpper Hull Front: 13mm.
Lower Hull Front: 6.4mm.
Upper Hull Sides: 6.4mm.
Lower Hull Sides: 6.4mm.
Hull Rear: 6.4mm.
Hull Top: Open.
Hull Bottom: 6.4mm.
Hood: 6.4mm.
EngineWhite 160AX 147 (Petrol)
Transmission4 Forward & 1 Reverse
Maximum Road Range198 miles (320 km)
Maximum Cross Country Range175 miles (282 km)
Maximum Water Range[@maximum_water_range]
Maximum Road Speed45 mph (72 kph)
Maximum Cross Country Speed9 mph (15 kph)
Maximum Water Speed[@maximum_water_speed]
VariantsM4A1 MMC:
Quantity: 600
Year: May 1943
New reinforced Floor to allow for vehicle firing
M21 MMC:
Quantity: 110
Year: January 1944
NotesBased on the half-track car M2 and built by White, the M4 carried a rear facing 81mm mortar, the mortar also carried a base plate for ground firing, as the weapons was only designed to fire from the vehicle in an emergency. This was changed with the M4A1 which added a strengthened hull to accommodate firing the weapon from the vehicle The M21 was based on the M3 and had a forward facing 81mm mortar. This allowed for easier firing and to maneuver the vehicle to a new position. The M21 was also built by White with 110 built between January and March 1944 before production was stopped.