I see this type of offering all the time. Seller thinks he has THE BEST of whatever ever made. Gets $$ in his brain and sets HIGH price. Is the M42 all factory original? Since M42's are not my specialty, don't know about the engraver but I don't think thier are records for M42's as for M21's. Then one needs expert appraisels. If not factory original, then its worth nothing as a high grade collectable. If factory, the price will be determined when cold hard cash changes hands but NOT from my hands.-Dick
