Well, they don't have to be a "machinist", per se, but someone who is definitely familiar and competent with S&Ws. The spring change is the easy part, but the other work - less is more when it comes to that and some people get carried away, mess up tolerance, make things worse. If you can network around and find someone in your area who has the proper aptitude and a fine touch, they could get it done. And let me tell you, it makes them sweeeeet to shoot when it's done.