Luger barrel Question

Ok after 13 years I finally decided to get a luger. It was supposed to be my first pistol but I got distracted. One of the local gun shops has a 1917 DWM all matching except magazine. It has been reblued because it is 100%. It has wood grips in nice shape not neww but good. The barrel has no proofs marks or numbers of any kind. On top of the barrel in front of the chamber is a gigantic proof punch mark about 1/8 in diameter. Is this a East German barrel. The front sight sleeve is not seated all the way down on the barrel. Can the sleeve be set down by using a wooden dol and hammering it in place. They are asking $600.00.

TIA

Barry