1/35 U.S. Mortar Carrier M21U. S. military planners experimented with half track designs from the late 1920s and employed several vehicles during WWII. Among them was the M21 mortar carrier, which was officially adopted in June 1943. It featured a frame on the fighting compartment floor for the mortar that allowed sixty degrees of left and right traverse. The vehicle was also equipped with a 12. 7mm heavy machine gun, bazooka, mines, and a wide range of other weapons. This model