Just went through this exercise last Spring...I own a 270wsm,7mm mag but I chose 260 AI...
26 inch barrel by Pac Nor, I am pushing the Berger 140s @ 3000fps
Anything under an Elk this is a very accurate/lethal combination shoots real well at 1000 yds.
This year an antelope found out @ 680 yds.
There is very lttle recoil so it's a blast to shoot the rest of the year.
I used a 3 groove barrel, just an idea, it cleans up great and shoots in the .4s @ 100 yds.