It sounds like you are comfortable with the BAR so use that. The 30-06 with premium bullets will do the job as far as than you can shoot accurately. Accuracy, recoil, and bullet composition are critical to lang range success far more than caliber, velocity, or energy especially when talking about .270 and larger. I had myself convinced I needed a 300UM as my one gun for everything. After much reading and studying I am simply going to do a bedding and trigger job and put a synthetic stock on my old Model 70 30-06. I have great confidence with that gun that no amount of increased energy or trajectory will overcome.