WW2 rework?

I think the answer lies in the echelon that did the repair and or refinishing. Often depot level (arsenal) level work will show a Hzaxxx type mark. I don't know the meaning of the Ku mark ...I think the jury is still out on exactly what that one means and where the assembly was done for the Ku Lugers, although I agree with you that it was not at a factory. I don't think (evidence does not support) that much of the WWII refurbishment was conducted at factories for any weapon...including Lugers. The most data is probably known on K98k's and of the several legit 98k reworks that I have inspected, none show newly added waffenampts..except sometimes to the wood (this is also true with the Hzaxx type stamps). Most German WWII reworks were performed by matching smaller parts to the frame number and sometimes this included removing the old number and perhaps replacing some parts with new ones. Sometimes existing numbers were missed (ie the saftey lever). Interesting subject which very little is published but must have affected thousands of Lugers.