I own several 260s with 8 twist barrels that I have built over the years and the 120 with H-414 powder is a magical combination, you just have to push the load to get the holes to come together. However, the 6.5 rifle does not need a heavy bullet to kill like a lightning bolt, just do not shoot to hit bone, a shot behind the shoulder or in the neck is an instant one shot killer.
Ed