Re: Barrel countor
I have the most experience with a M40 contour and Rem. Varmint contour in .308. I don't see a lot of reason to go heavier than the M40 on a rifle that you will be walking with. I like the Varmint contour just fine though and don't feel that the contour of the barrel is the limiting factor in the accuracy of the system.
I was at a Museum in Louisville, KY looking at a firearms exhibit. Some of the "target" rifles they had in there were baffling in their mass. Barrels like telephone poles. Of course they were working with some different ammo and some different notions about things.