223 and barrel twist

I have not shot any 80's yet, but I am running 77 Scenars in a 1-9 with great results. Berger has a twist calculator on there site that works pretty well. You might want to enter some data and look at the projected SG.
 
8 twist is fine for 80's. I put 5k+ of 82 Bergers on my Brux 6.5 twist, and the new barrel is 7 twist, just because. I'd have had no problems substituting an 8 twist instead...
 
The 80gr A-Max can be a fuzz marginal in a 1:8 (especially at low elevations and cold temps) due to their length, but Bergers or SMK/CCs would be just fine as mentioned upthread.
 
When in doubt read the end of the box.

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I went with a 1 in 7 in case I ever wanted to try the 90's but the 80.5 Fullbore berger have shot so exceptionally well I have seen no reason to shoot the 90's. When in doubt go with the faster twist. A little more twist is better than not enough.