Re: 7mm vs. .30 cal
A 30 cal built on the same 7mm case with the same barrel length will typically get better velocity due to burn area. A 30 cal hole is bigger. It is a simialr principal to adding length to a barrel. More burn area, more velocity.
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.