BROWNING MACHINE GUN, CALIBER .50, M1921, WATER-COOLED 1932 TR 1300-50B INFANTRY AND AIRCRAFT ARMAMENT. BROWNING AIRCRAFT MACHINE GUN, CALIBER .50, M1921 1931 FM 23-60 BASIC FIELD MANUAL, BROWNING MACHINE GUN, CALIBER .50, HB, M2 GROUND 1940 FM 23-65 ARMY FIELD MANUAL, BROWNING ...