The publication of any images or informations related to nazism, fascism or any other totalitarian regimes must be understood as the reproduction of historical accuracy and not as apology to these regimes, leaders or symbols.
A publicação de qualquer imagem ou informação referentes ao nazismo, fascismo ou quaisquer outros regimes totalitários deve ser entendida como reprodução do rigor histórico e não como apologia a estes regimes, líderes ou símbolos.

M40 Gun Motor Carriage 155mm (T83) - case report

      This time, our character is a vehicle that appeared in late stages of World War II, but with a great punch: the M40 Gun Motor Carriage 155mm (T83). I built this girl in 2006.
M40 Gun Motor Carriage 155mm firing... Korean War.
      During World War II, the need for rapid displacements, stemming from the hard lessons learned by the Allies through the Blitzkrieg, forced the development of a whole philosophy of self-propelled artillery. The Americans were well served in this field with some reliable and sturdy vehicles. It can be mentioned, like the most characteristic of them, the M7 Priest, that carried a 105 mm M1/M2 Howitzer. This GMC (Gun Motor Carriage) was the backbone of the American Self-propelled Artillery. This vehicle was based on the chassis of the M3 Lee tank.
M7 Priest SPG 105mm
Normandy, 1944.
      With the development of the conflict, the need for larger caliber guns led to the development of the M12 Gun Motor Carriage, also based on the chassis of the M3 Lee tank, but carrying a larger caliber guns: the M1917, derived from the French WWI rapid-firing gun. The M12 GMC 155mm added a greater weight to the American self-propelled artillery.
M12 GMC 155mm in the snow
      But as the M12 carried a World War I weapon, the stockpiles of these guns were lowered rapidly, by the intense and necessary use. The US Army has chosen to replace this obsolete weapon with a more modern, longer range and more reliable gun, albeit of a similar caliber: The M1 155mm Long Tom.
M1 155mm Long Tom in action
      The M3 Lee chassis was no longer load-bearing to absorb the weight and energy released by the 155mm Long Tom firing. It was then decided to use a widened and lengthened Medium Tank M4A3 chassis, but with a Continental engine and with HVSS (Horizontal Volute Spring Suspension), which was introduced at the end of the World War II.
M4A3E8 "Easy Eight" in action
      The vehicle coming from these modifications was a natural evolution of the M12, although totally different in its design. Initially designated as the T83 Gun Motor Carrier, its construction began in March 1944, when 5 pilot vehicles were built, with the tests demonstrating the correctness of the concept and design, with a perfect marriage between the gun and the chassis. The T83 was accepted to enter into standardized production in February 1945, and in March 1945 its designation was changed from T83 to M40.
      A single pilot vehicle was used in the European Theatre in 1945 by 991st Field Artillery Battalion, along with a related 8 inch Howitzer Motor Carriage T89, (later re-designated the M43 Howitzer Motor Carriage), in the capture of Cologne (Zebra Mission).
M40 (T83) - The single vehicle used in WWII
Notice the cammo (OD with black stipes)
Koln, March,-1945.
M43 (T89) 8' (203mm) - Heavy Howitzer
      One lesson of this first battle test was that the open fighting compartment left the gun crews very exposed to enemy fire. General Barnes, commander of the Zebra Mission, suggested that some effort should be put into produced some sort of armour to protect the crews, and also that secondary machine gun armament be installed. An armoured cab was designed, but it wasn’t considered suitable.
M40 with armoured roof
M40 firing in the Korea War
      A complete gun section consisted of one M40 GMC and one M4A1 high speed tractor towing an M23 ammunition trailer. Each battery had four gun sections. The M4A1/M23 combo replaced the earlier T30 cargo carrier (see below).
      A handful of M40s reached the front where they replaced worn-out M12s, but their main combat use came during the Korean War, where both the M40 and M43 proved to be invaluable during the long stalemate on the 38th Parallel. After the Korean War the M40 was withdrawn from front line service in the US Army.
      After World War II, the M40 was used by the British Army, who designated it 155 mm SP, M40 Cardinal in the tradition of using ecclesiastical names for SP artillery, such as DeaconPriestBishop and Sexton.

The Army planned to use the same T83 chassis for a family of SP artillery:
  • Cargo Carrier T30 - a few built before cancellation in December 1944 to make more chassis available for GMCs
T30 cargo carrier
tractor and ammo carrier based in M40.
8 inches HMC M43
  • 250 mm Mortar Motor Carriage T94 - 10 in (250 mm) MMC, began design Feb. 1945, one prototype completed in 1946
250mm MMC T94
M40 described:
      M40 was based on the chassis of the M4A3 with horizontal suspension HVSS. The hull was lengthened to provide a sufficient compartment of combat to accomodate the howitzer of 155 mm. The tank was divided into three parts: the cockpit in front provided with two cupolas of vision on the roof (as well as a trap door of escape on the floor) for the driver and codriver/radio operator.
Driver station in M40/M43 SPG
      The engine compartment in the center and the compartment of combat to the back which occupies half of the length of the tank. The M40 had a crew of 8 men which the driver and the codriver who took seat in the cockpit. The remainder was divided between the station of combat and an ammunition carrier.
      The armament of M40 consisted of an howitzer of 155 mm M1A1 or M2 on M13 mount installed to the back compartment. This weapon had a maximum range of 23 km. M40 embarked 20 projectiles of 155 mm. M40 was equipped with a broad door with back folding back with a slope of loading/access where the 6 gun crewmen can operate at ease, and which facilitated the loading of the ammunition. Like M12, this motorized howitzer was equipped with a broad spade to the back which inserted in the ground prevented the tank from moving back because of the recoil of the weapon at the time this one was used.
      The engine installed in the middle was Continental R975 C4 gasoline of 9 cylinders developing between 400 and 460 hp to 2400 rpm. M40 could reach on road the 39 km/h and with the 976 L embarked to run approximately 160 km on its own fuel. 

      The suspension of the type HVSS (Horizontal Volute Springs Suspension) comprised 3 pairs of bogies provided each one with two double-road wheels, a pair of back idlers, a pair of front sprocket-wheels and five pairs of return rollers. The tracks assembled with suspension HVSS was broader than those assembled on suspension VVSS (Vertical) and reached the 580 mm broad. 
HVSS - Horizontal Volute Springs Suspension
      This provision ensured the tank a better stability and a pressure on the ground acceptable . The horizontal suspension resisted better to the recoil of the gun as the vertical suspension.

Types of tracks assembled on M40:
T66 type: central guide, single pin, steel, rubber
Width: 580 mm - Pitch: 150 mm - Links: 2x79 - Track ground contact: 3.84 m
T80 type: central guide, double pin, steel, rubber
Width: 580 mm - Pitch: 150 mm - Links: 2x79 - Track ground contact: 3.84 m
T84 type: central guide, double pin, rubber
Width: 580 mm - Pitch: 150 mm - Links: 2x79 - Track ground contact: 3.84 m

      The shielding of M40, was very light and did not exceed the 25 mm. Only the two drivers were entirely protected in the cockpit whereas other crewmen were very exposed in the open (top and back) combat compartment. Since M40 practically operated like a traditional piece of artillery, i.e. since the rear lines, at long distance, this defect (desired to spare the suspension and the mobility of the tank) had only little importance.
      A total of 418 M40s were manufactured in 1945 by Pressed Steel Car Co which 24 were converted later into M43. M40 replaced little by little M12s and their old guns of 155 mm dating from the WW I.


M40 Gun Motor Carriage 155mm
TypeSelf-propelled artillery
Place of origin             United States
Weight36.3 metric tons
Length9.1 m
Width3.15 m
Height2.7 m
Crew8 (Commander, driver, 6 gun crew)

Armor12 mm
155 mm M2 gun
20 rounds
EngineWright (Continental) R975 EC2
350 - 400 HP
Power/weight9.36 hp/t
SuspensionHVSS (Horizontal Volute Spring Suspension)
170 km
Speed38 km/h on road
23 km/h off road

The kit:
      As I said, I built this girl in 2006. The only option was the AFV Club #35031 M40 Big Shot.
      Inside a sturdy cardboard box, the olive styrene pieces come packaged in thermo-sealed plastic bags, plus a zip-lock wrapped sachet for the trowel winch mechanism and an excellent photo-etched plate.
The lower hull is in one piece, thin and without defects.
It is protected from damage by a white cardboard box
with the vehicle profile

Transparencies that allow the assembly of the visors of the turrets, periscopes and taillights.
Strangely, headlamps do not have transparency or even lenses of this material (???)
Cupolas in dry-run

The tracks are  T66, in very soft vinyl, with an excellent detailing.
Its glue can be made with styrene glue or cyanoacrylate.
The kit also comes with an excellent aluminum gun.
The metal gun in detail....
A good booklet
      And a very good sheet of decals, with 3 versions of M40: One Zebra Mission and 2 from Korea War.
Decal sheet: very good!!!
      I started the assembly by the gun, following the instructions. Glue the aluminum tube to the plastic base with cyanoacrylate. Be careful of the alignment of this part.

      The instructions point to gluing all the accessories onto the holder and then docking the gun in this cradle, but I reversed the order in this step: Manipulating the gun with so many delicate pieces could generate "accidents". I placed the gun in its cradle, and then I mounted the accessories (lifting wheels, sights, etc.)

      The suspension is all articulated, arms moving independently in the bogies. Although it can facilitate the detailing in a diorama, the presence of the vinyl tracks usually traces this suspension, forcing it into a strange position. I chose to glue the extreme bogies, leaving only the medium bogie with movement. The vinyl pieces are embedded inside the bogies:

Bogies almost ready!!
The bogies has casting numbers. Good detailing...
       Starting the upper hull...
The cockpit painted in white (inside...)
Starting the combat compartment...

My choice: combat compartment in open position.
Spade lowered

Installing the rear cover cabling...

Cockpit and engine compartment...
Cupolas in close...
Chassis done. Now, it's painting time!!!
       My girl was WWII, of course! Zebra Mission!!!
Wheels under painting..
Olive drab with black stripes: Zebra Mission!!!

       And the girl was almost done!!! M40 GMC 155mm - 991st Field Artillery Battalion - 3rd Armored Division - Cologne, Germany. 1945.
M40 GMC 155mm

      A major flaw in this kit: The AFV does not provide any 155mm projectile with the vehicle !!! Simply ridiculous !!!
No shells!!!

      But I decided to rebuild the vehicle in transport position, to save space on my (crowded) shelf !!

M40 GMC 155mm (T83)
991st Field Artillery Battalion - 3rd Armored Division
Cologne, Germany. 1945
M40 GMC 155mm (T83) - left side

M40 GMC 155mm (T83) - right side

M40 GMC 155mm (T83) with kojak and Rover, the dog.

Two heavy guns from 991st Field Artillery Battalion
M40 GMC  and M12 GMC: girls with 155mm attitude!!

M40 GMC 155mm and M12 GMC 155mm
M40 GMC 155mm (T83)
991st Field Artillery Battalion - 3rd Armored Division
Cologne, Germany. 1945

See you soon, Gents!!!