I have an AR-10 bolt that I need to bush the firing pin on. The bolt seems at first examination to be fairly hard, too hard to machine with high speed steel. Anyone know if it's through hardened or case hardened. The second question is, does any one know what Armalite did for the bolt in their .300 SAUM rifles. Obviously, open the bolt face, but what of the extractor? I want to build a 7MM SAUM upper, will do the barrel work myself. Any info would be appreciated. I realize that this is primarily a bolt action crowd, but their's a lot of experience here!