I guess the thing we will really never know for certain about the history of the rifle without going back to the previous owners. I know the Japanesecaptured well in excess of 200,000 M1917 rifles which were supplied to the Philippine Army in the late 1930's. Without going back to the owner who sporterized the rifle its going to be impossible to determine specifics.
--fjruple
PS-- Having seen the fully engraved Colt SSA Revolver you could not but love the workmanship on the revolver. I wish it was mine, I was considering having one done myself but I was leaving for back in the States.