The M1A1 kit i bought over a 15 years ago had a back third, the nose portion /barrel and hand guard bar , the rest was missing of the recevier. It was torch cut everything else was unmolested . I spent some money with Doug Richardson for one of his complete front machined receivers barrel threaded, feed ramp ,ejector timed , bolt nose pierced through to the bolt pocket which was lightened with 3 bored pockets almost to depth . It was spendy but the fit , finish and hardness is spec and beautiful ,if it were legal it would take only a few hours to finish the bolt pocket on a mill . Unfortunately they are no longer available !!