Re: 26" vs 28" in a 300WSM
Personally I like the longer barrels because they offer xtra speed, less muzzle blast and if no brake is used less muzzle presure to smack the bullet on its exit for even greater accuracy potential.
For the short action, you can afford to carry an extra 2" of barrel.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.