The Chinese Gladiators used the American M1919 Browning machine gun to fire the American .30-06 Springfield which was the main ammunition of the Chinese Nationalist Air Force. By February 1938, these aircraft had been assembled into two squadrons and the Chinese pilots familiarised themselves with them.[19] The Gloster Gladiator had its combat début on 24 February 1938.[20] That day, in the Nanking area, Chinese-American Capt John Wong Sun-Shui (nicknamed 'Buffalo') shot down an A5M Claude navy fighter, a Gladiator's first victim. Wong is believed to have shot down a second A5M, for the wrecks of two Japanese fighters were found.[20] During that clash, Chinese Gladiators lost two of their number.[21]