Left fall ASSRA matches due to unertl rear scope problem  would"t tighten   experts there said the threads were stripped  dare I try to retap them with a 6-40 tap??   also 6-40 screw in bad shape and needs to be replaced   the 6-40 screw moves freely in the larger nut which screws into the mount   is this a problem  dick eesley@yahoo.com