The M1917 Enfield, the "American Enfield", formally named "United States Rifle, cal .30, Model of 1917" is an American modification and production of the .303-inch (7.7 mm) Pattern 1914 Enfield (P14) rifle , which was developed and manufactured during the period 1917–1918. Numerically, it was the main rifle used by the American Expeditionary Forces in Europe during World War I.