I need to know what match grade barrel i need. Im building a 300 win mag. Rem. 700 action. Im thinking of a 30" stainless barrel. What twist rate do i need?. I will be shooting 180gr to a 200+gr bullet. Any ideas on what powder to start with on reloading. h1000? Ive been out of shooting for a good while, and im having to relearn all the stuff. lol