the 1917 was basicly a P14 made to fire a 30-06 round, since the P14 was made for the Brits, it was built for them threads and all, when they made the M1917 that was one thing they didnt change,
they even left the off set sling swivels for the long range sight on the P14..basicly changed what ever parts were needed to make the rifle fire 30-06.
however, more then you might think is different P14 VS 1917...but thats best left for another post, and has been discussed before.