The MS-1 had a hexagonal turret with slightly sloped vertical armor and a commander’s cupola on top. The armament was placed in the front part of the turret: the gun to the left and the machine gun to the right.

How to Get MS-1 Turret
B-3 37mm + Rolled

MS-1 Turret Doodle Tanks Combo
+Rolled = BT Turret
+Welded = Sloped
+Infantry Tank Hull = MS-1