The goal will be 1200yd+ Prairie dog hunting. I wouldn't mind something like a 6mm but at that distance wind starts to take a heavy toll.
7mm bullets, i like the extra weight, but after running the numbers in shooter the 6.5 is a bit better and its lower recoil and less powder. if i was hunting game id use 7mm but since they are prairie dogs, 6.5 is 100% fine.
i dont have an action picked out yet so magnum vs long action vs short action isnt really a consideration. im thinking that i like .264 magnum so far but im not married to it.
my 'wish list' would be
1. available brass
2. minimal prep (non-fireformed over fireformed for example)
3. barrel life
4. recoil/efficiency (example would be a cartridge that has 10gr more powder but only 50fps more)
if i know the drawbacks i can work around them. if its a barrel burner, id build on a savage action and get a quality pre-fit barrel from some place like shilen to swap myself vs having one made by GAP locally for ~750-800.