M12 King Kong

T6 pilot vehicle. Note the wide profile of the rear spade compared to production models.

Studies of an SPG based on the M3 medium chassis mounting a 155 mm gun were conducted in June 1941. At the time, artillery doctrine envisioned the use of towed guns, so there was little use for a self-propelled weapon. But after discussions between the Field Artillery Branch and the Ordnance Department allowed for the construction of a pilot vehicle. This vehicle would be designated as the T6 GMC. The pilot was delivered to Aberdeen on February 12, 1942.

Firing tests showed the T6 to be a stable platform for the 155 mm M1918M1 selected. However, the rear spade was damaged during tests. Even retracted, the protruding space was a limiting factor to cross-country mobility. The spade would be redesigned and after modifications, the T6 pilot was sent to Fort Bragg for tests by the Field Artillery Board. These tests showed the superiority of a self-propelled mount in supporting rapidly moving formations. Finally, after so much push-back over the years, a heavy SPG was allowed to be adopted. The production vehicle would be standardized as the M12 GMC.

Production model M12.

The M12 was complemented by an M30 cargo carrier, which a similarly based on the M3 medium chassis and would follow the M12 to provide support and carry ammunition. 100 M12s were authorized for production. With buildup for the invasion of Normandy starting, 74 M12s would be modernized in December 1943. The M12s would be seen across Europe, including Normandy and the Siegfried Line.

An M12 alongside an M30 cargo carrier.

The vehicles could carry either the 155 mm M1917, M1917A1, or M1918M1, depending on availability. These weapons were completely interchangeable with one another. The gun mount for these weapons could traverse 14 degrees to the right and left, and had an elevation range of +30 to -3. After supply of these 155 mm guns was exhausted, a 155 mm Gun M1 was experimentally mounted on an M12. However, the chassis was unsuitable for the comparably more powerful weapon. A new SPG based on the M4 medium would be designed to carry this gun, giving rise to the M40.

This tank is represented fairly accurately in-game, really. All I can consider doing is removing the top engine, which I don't think the tank ever had or really even needs. I would perhaps consider improving its accuracy and/or aim-time in exchange for a slight nerf to its reload speed.

Guns: 155 mm Gun M1918M1; 155 mm Gun M1

Engines: Continental R-975E-C2 (400 hp); Continental R-975-C4 (460 hp)

Suspensions/Alternate Hulls, Total Weight (metric tons): M12 (26.76); M12 Modernized (26.76)

Hull Armor (mm): 51/20/20

Top Speed: 34 km/h

Crew: 6 (Driver; Gunner; Loader; Loader; Commander; Radio)




Parent: Holt Mk. IX
Children: T79/T80

Sources:

Hunnicutt, R. P., Sherman, 1995