Ahh, but here's the rub. The legality of the gun would be in question in the eyes of a liberal, and some moderates. An ATF agent may seek to pursue this issue in a court of law, with your friend up on some sort of felony charge. The gun would be temporarily forfeit, and in the end, likely lost or damaged beyond repair.
Have him take it to a reliable gunsmith, and avoid the possible legal implications.