Browning Machine Guns, Caliber .30 inch, M1917A1, M1919A4, and M1919A6 - USA Voorschrift, Field Manual, 23-55 Browning Machineguns Caliber .30 inch, M1917A1, M1919A4, M1919A4E1, M1919A6, and M37. FM 23-55
