The largest bullet I have ever seen with a 270 was 160 gr. I would recommend 150 grain unless you are an accomplished handloader. I would limit shots to 200 yards (250 max if coditions perfect) and I would wait for a broadside or slight angling away shot and shoot half way up the body just behind the shoulder (double lung shot). I would not want to try a shot through the shoulder with a 270. Good luck