I am looking for a way to legally convert an ar15 to a gi style m4a1. I am a class 2 gunsmith so i can legally manufacture all of the parts necessary. I also have a cnc mill if i need to manufacture parts in a precise manner. I would appreciate it if someone can list the parts and procedures necessary to do so. It would also be good if there was a book about it as well. I would like this to be like the m4a1 i had in the marines. Any help is greatly appreciated.