I have made up my mind to build a 338 edge out of my Remington 700 7mm.I'm not a greenhorn when it comes to shooting or reloading but With this being the first gun I've ever built I don't know how this process works. When i choose which barrel I want do I need to contact the barrel maker and send them my barreled action and have them fit it to my action or do I order the barrel and have a gunsmith fit the barrel to the action.