[mrerick]

Your Luger is constructed from multiple donor Lugers, so the actual assembly date can never be determined.

I can't make out the suffix letter under the 751 on the front of the frame, so can't tell you the approximate period the frame was made. Unfortunately the receiver may also have been renumbered so it might not be during 1917. Better lighting and focus would help. Note that the suffix letters were repeated during Luger manufacturing.

Your Luger is refinished, and the barrel is from another donor pistol. If the receiver was renumbered too it came from a different donor pistol than the frame. The receiver looks like it might have been renumbered.