 Development on a new 76 mm gun better-suited to the Sherman began in fall 1942.In early 1942, tests began on the feasibility of mounting a 105 mm howitzer into the turret of the Sherman.The basic 105 mm howitzer M2A1 was found to be ill-designed for mounting in a tank turret, so it was completely redesigned and re-designated the 105 mm howitzer M4.