The shortcomings of the Type 97, with its low-velocity 57 mm gun, became clear during the 1939 Battles of Khalkhin Gol against the Soviet Union. The 45 mm gun of the Soviet BT-5 and BT-7 tanks out-ranged the Japanese tank gun, resulting in heavy Japanese losses. This convinced the army of the need for a more powerful gun. Development of a new 47 mm weapon began in 1939 and was completed by 1941. The Type 1 47 mm tank gun was designed specifically to counter the Soviet tanks. The 47 mm gun's longer barrel generated much higher muzzle velocity, resulting in armor penetration superior to that of the 57 mm gun. The new version, designated Type 97-"Kai" ("improved") or "Shinhoto Chi-Ha" ("new turret" Chi-Ha), used the 47 mm main gun in its new, larger three-man turret. It replaced the original model in production in 1942. In addition "about 300" of the Type 97 tanks with the older model turret and 57 mm main gun were converted.