Re: Bullet weight and length choice for a 1:14....
Now that I know you are punching 600 yard paper, I would use the 155 Palma or AMAX loaded as fast as you can get accuratley. The 155's are a good comon sense bullet for the 308 but shooters seldom use a twist that is optimum for the 155. From your 25" bbl in 14x I would expect around 2900-2950+ FPS which is very good. If ussing a 308 winchester try RL-15, VARGET, or IMR4064 in that order. The 155 Lapua Scenar might stabilize in your barrel or might not. I havnt tried that bullet in a 14 twist. If it stabilizes and you get good accuracy it will have the best BC of the 155's. An honest .495-.510. With your twist and bbl length I would guess it to be around .500-.505.
Long range shooting is a process that ends with a result. Once you start to focus on the result (where the shot goes, how big the group is, 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.