Carbine Club members have known since 1986 that there is a documented pristine example of an SG with the same hammer with a serial number very close to the OP's. If the best answer is what's sought, is it too complicated to go to the best source? Others can rely on Riesch which in many cases is like using a yardstick in place of a micrometer. The decision by Riesch's publisher to do piddling changes instead of a serious revision in light of new info is shameful.