M3 GMC

Notice the limited protection of the original gun shield.

The effective employment of German armored forces was a subject of serious study following the fall of France in 1940. For the United States, it was suggested that the best way to combat a mechanized force would be with specifically designed anti-mechanized units, with emphasis on firepower, mobility, visibility for the gunner, and little armor. While these specifics would go on to dominate US tank destroyer philosophy for the duration of the war, at the beginning of 1941 there was little available in the way of guns or chassis for such a self-propelled weapon, and the process of designing and producing a special-built tank destroyer would take at least a year. But the US needed tank destroyers now.

As for guns, the US had a ready supply of the 75 mm M1897A4, a modernized version of the French M.1897 field gun used throughout WWI. At the same time, the M3 Half-Track was just coming into full production. On 25 June 1941, a project was initiated by Ordnance to create an expedient tank destroyer using these two items. This would make good use of existing stocks of the old field gun and would create a suitable tank destroyer by the fall of 1941, where 50 would be rushed to the Philippines in defense of the islands. This new vehicle was designated as the T12 GMC, and would later be standardized as the M3 GMC.

M3A1 GMC with the modified gun shield.

Modifications of the half-track included completely removing the windshield and installing an armored cover that could be folded down on top of the hood. The fuel tanks were also relocated and a steel base was installed to support the weapon mount. The gun could traverse 19 degrees to the left and 21 degrees to the right, with an elevation range from +19 to -10. Later tests would also replace the early gun shield with something larger that offered better protection, resulting in the M3A1 GMC.

Production would run from February 1942 until April 1943, for a total of 2202 vehicles. In Early 1943, the supply of the M1897A4 field gun had been exhausted. In March, authority would be granted to use the 75 mm Gun M3 being used in the M4 Sherman. This vehicle was given the designation T73, but was ultimately cancelled.

T73 GMC.

This vehicle is pretty much a straight upgrade to the M2 GMC in terms of firepower. Otherwise, they're practically identical. Along with its mobility, the increased firepower makes the M3 GMC a formidable opponent at Tier 3, but the gun handling should be lacking compared to its peers. But since the armor and mobility are effectively unchanged, the vehicle is even more fragile tier-for-tier than its predecessor.

Guns: 75 mm Gun M1897A4; 75 mm Gun M3

Engines: White 160AX (147 hp); IHC RED 450 (160 hp)

Suspensions/Alternate Hulls, Total Weight (metric tons): M3 GMC (9.07); M3A1 GMC (9.3)

Hull Armor (mm): 13/6/6

Top Speed: 72 km/h

Crew: 5 (Driver; Gunner; Loader; Commander; Radio)




Parents: M2 GMC
Children: T48 GMC
See Also: M9 Half-Track, M15 Special, M3 DEFA

Sources:

Hunnicutt, R. P. Half-Track, 2015.