the M1917 was based on the Pattern 1914 enfield which was supposed to replace the Lee-Enfield. it was thought before WW1 that the Lee wouldn't be an ideal infantry weapon ( how wrong they where ) and requested a mauser type replacment also chambered in .303 british. the US Army got interested and asked for a .30-06 verson that was adopted in 1917. they're also popular for building customs on my granddad had one rebuilt in .338 and it was a sweet shooter