The barrel and receiver appear to be of new East German production. The East Germans produced 100 complete new Lugers in 1953 on captured equipment.
Here is a beautiful and rare example from Mark Castel's collection. The receiver exhibits the same characteristics as the one posted.
http://www.p38guns.com/EGLugerRig.htm
As Dwight states, VOPOs are becoming collectable in their own catagory. Prices range from $700 to over $1000 for nice and / or unusual examples. This one would fall in the "unusual" catagory IMO.
Ron