They (the Isrealis) would force match the BCG with E.P.'d numbers. Then they stamped the tiny Star of David and the "y" style stamp and then parkerized just about all of them. I suppose really nice numbers matching guns did not require a refurb so they still have their original blue finish. I don't know if those have the Star of David and the "y". Not sure when they white rubber stamped some of them. Perhaps when they were assigned to certain units.