I haven't personally built any long range rifles but I have had a few built for me. I would go with a hart or Krieger barrel. If you're not concerned with weight, about a #9 contour would be excellent; lots of shooting and good accuracy. I have a 24" #4 contour Krieger stainless barrel on my 270WSM. The rifle weighs about 8.5 lbs scoped. I did own a 300WM rifle with a #9 contour stainless fluted 24" Krieger barrel. The gun weighed 14 pounds in an HS Precision stock with a 30mm Leupold scope. Mcmillan and HS Precision make the best stocks out there and I've heard that Bell and Carlson stocks are good for the money; much less expensive than the other two. You definitely want to glass bed and "free float" your barrel. There is quite a bit of information available on line about that process. I would take a look on Midway USA's web site. You can find literally everything you need there.