Bob
I'd ask what are you planning on hunting.
If your interested in 160 and 170g bullets your going to have to speed up your twist.
With your 270/300 you know very well how effective 130/140 bullets are.
What would 160/170g bullets gain you.?
dave
Just me, but I'd go 7.5 twist and shoot whatever you want. You won't hurt a Barnes or PT but you'll gain RPM's if you decide to try heavier stuff.
