Waste of time and money. Who ever heard of "lapping" aluminum? Stoner designed this weapon with RAM Logic so it could be maintained in the field without a myriad of precision toola and specifications. The Army figured out long ago that any M16 out of the rack can be issued to a non-shooter along with 8 hrs of basic markmanship can achieve battle sight zero and engage and hit targets at 300-350 meters away with open sights.