Copy of book that is. I’m not sure on who made what. I do know that he stated his barrel, and receiver, op rod, etc. are all marked with either qlv, or the appropriate WA 20 for Erma. So, it might very well be that Erma didn’t do the Receiver pressings….but just the block as well as other machined parts. Then Mauser held the Stamped flats ready to be built up into a gun using mostly parts from each supplier? I just put an offer on one of these books….so hopefully I can find some answers.