This bolt lapping business got pretty heated awhile ago, mostly with the M14 guys. Tim's stand was always avoid lapping. I had an Armscorp receiver that the lugs were over 10 thou off from each other. Lapping would have went through the heat treating. Anyway, interesting WRA receiver that maybe fell victim to bolt lapping?
http://forums.thecmp.org/showthread.php?t=153761