It's done by changing out the barrel. If you go with a top quality barrel I'll usually charge around $550 complete. ($300 for barrel, $250 labor). If you find a factory takeoff .260 barrel it's about $200 for labor only. You'll find a wide range of prices around the country, and a wide range of quality of work. Most of the barrel makers (Shilen, Pac Nor, ER Shaw, Douglas, etc) offer rebarrel services, and any gunsmith worth the title can do it. As for the teflon finish, I've been using that Brownells bake on teflon recently with good results. There are lots more out there such as Robar NP-3 and Lauer Duracoat as well.