Near the end of World War II, more experimental versions of the 90 mm gun were tested including the even higher velocity T18 and T19 main guns. The T19 was a T18 modified in an attempt to reduce barrel wear. Other versions included the T21, which was intended for wheeled vehicles, and the T22, which used the breech from the standard 105 mm M2 howitzer. The T21 and T22 were designed to use larger powder charges. None of these versions entered service.