I am gonna go out on a limb here and say I highly doubt even commercial 1917's were shipped with Magnas. I believe the commercial guns were probably shipped with checkered service type grips with medallions.

Magna grips predate WW2 by a few years, but there is a noticable difference between the pre-war variation and the post war grips on your gun. Below is a picture of a set of pre-war magnas.



Hope this helps