Modelling the US Army M4 (76mm) Sherman Medium Tank

A 'quick and dirty' historical guide

The US Army introduced the 76mm gun on the M4 series to improve its firepower (the history of this program can be found in Osprey New Vanguard 73). The first of the 76mm versions, the M4A1 (76mm) entered production in January 1944. The M4A1 (76mm) initially appeared in combat in Normandy during Operation Cobra in late July 1944, and one of these tanks will be the subject of our first project here. The 76mm gun was also adapted to other versions of the Sherman family, the diesel-powered M4A2 and the Ford-engined M4A3, but neither the M4 nor M4A4 versions were armed with the 76mm gun. The M4A2 (76mm) entered production in May 1944 and was widely used by the Red Army; but it was not used by the US Army and so is not covered here. The M4A3 (76mm) entered production in March 1944 and was by far the most common 76mm gun tank of the US Army in 1944-45. It first appeared in the European Theatre of Operations (ETO) in August 1944, though it did not become common until the autumn of 1944.

The 76mm tanks underwent continual technical improvements during their production run. The initial production versions used the D82081 turret with a D94598 two-piece split hatch over the loader's station. This turret is popularly called the 'T23' turret by modellers since it was originally designed for the T23 medium tank. The first batch of M4A1 (76mm) tanks were fitted with the basic M1A1 gun, which had a smooth barrel. Since the army planned to introduce a muzzle brake on the 76mm gun, it was modified by threading the end of the barrel so that the muzzle brake could be screwed on later once it became available. To prevent these screw threads from becoming damaged, a thread protector was fitted to the end of the barrel, resulting in the M1A1C gun. An internal change in the barrel grooves resulted in the M1A2 gun during the 1944 production, but this is not different externally from the M1A1C. These guns with the thread protector were the standard versions of the 76mm gun in production through the autumn of 1944. When the muzzle brake was finally ready, it was introduced into service on the M1A2 gun but without a designation change. These first appeared on tanks manufactured around September 1944. It is worth mentioning that some minor technical improvements were not necessarily sequentially applied in the assembly plants. There were transition periods when new parts commingled with older parts. The tank assembly plants received sub-components such as guns, turret castings, and bogies from sub-contractors, but in some cases, newly arrived components (such as a 76mm gun with muzzle brake) might go on a new tank, even though there were still some older guns in the plant without the muzzle brake that would then go on a tank built a few days later. Another point worth mentioning is that assembly plants tended to rely on certain sub-component plants for their assemblies. For example, Pressed Steel Car, which manufactured the M4A1 (76mm), typically used turret castings from Union Steel Castings (USC) while the Detroit Tank Arsenal, which built the first 1,400 M4A3 (76mm) through August 1944, relied on American Steel Foundry-Granite City and Continental-Hubbard for its supply of turrets. These castings often differed in small details from one facility to the other, such as the location and style of casting numbers.

During the course of production, a modified version of the 76mm turret was developed, the D90018. The main change on this version was the substitution of a new 24in.-wide oval loader's hatch in place of the split loader's hatch, but there were numerous small shape and detail changes as well. The D90018 turret first appeared on the Pressed Steel Car M4A1 (76mm) and M4A3 (76mm) tanks around August 1944.