.308 seems to do the job for me....one of the most accurate calibers hands down and doesnt kick too bad. I would go with at least a 30 caliber so you dont have to spend too much time looking for one you didnt hit good. I think the snipers use .308 and .223's. Just my two cents, but everyone has a favorite rifle. If you hit em right it doesnt matter. I say save your money and get a bow since you already have a 270. you will get addicted to bow hunting and sell your rifle.