Re: 80gr or 75 amax
What twist is your rifle? That's the main factor. I'd run the 80's if you have a 1-8 twist. There pretty close to even at 600 yards.. but...out to 1k the 80gr seems to work better for me. And the 75gr'er would run better with the 1-8 as well.
Remember, if your going to push the round hard the suppressor will add a little back pressure to your over all peak pressure.