Numrich used to sell a .22 conversion kit for the 03 with an M2 bolt, a slip in barrel liner, and a magazine. I had one but never put it together. But I do remember that no gunsmithing was needed. Do not recall whether the bolt was as=issued or had been modified, I think it was unaltered. It was years ago but I think there was an instruction sheet, if someone has one of these kits they could xerox it for you.