You really should post this at the M1917 and Pattern 1913/1914 Rifles sub forum.
Is this rifle in military configuration? is it sporterized? Bubbaed?
M1917 rifles were chambered for the U.S. .30 cal (30-06) cartridge as manufactured.
Post the receiver markings and some pictures for further help, you haven't given enough info to be any more helpful.
Here are some web sites:
http://www.odcmp.org/503/rifle.pdf
M1917 Enfield - Wikipedia, the free encyclopedia

D.