[DonVoigt]

That is good on the pin.

Nothing in these pictures helps, it quite likely simply a reworked alphabet commercial luger, dating to the 1920's. The usual proof mark on the left side of the chamber seems to be missing(need a good close up of this area), I cannot see it in the one angle view showing the area. This could have been removed during a re-finish if indeed missing.

The barrel was changed, somewhere, some time- with care- by someone who took the care to number the barrel and receiver. Why we won't and can't know.

To be certain the frame is consistent with the 1920 production, pictures of:

The inside of the frame from above showing the area in the well that the take down lever goes through, and the inside rear, between the "ears", from the front toward the rear will help.
Also a picture with the grips removed, and of the rear grip frame from the back.