Once I replaced the stocks with B&C's and skim bedded them, replaced the trigger in two and a spring in the third (rather than a new trigger) my 223 tac, 308 tac and 308 AAC all shoot well. Well being in the .5-.6 range. I have found the 1:9 twist in the 223 to really like 69 and 77 BTHP's, going to bullets longer than 1 inch can get tricky... if you search my "posts started" you will find one where I took the 223 tactical to 1000y with 75g berger vlds.
If you still have your AAC dont try to reach the lands... 168-175 BTHP, 168 a-max and 168 vld I have tried worked well when OAL was between 2.810-2.835 using varget, AR-comp and H4895. Watch your concentricity and I would not recommend going lighter than 155 and even that has been a little more finicky for me in the 1:10 twist AAC barrel compared to the 1:12 in my tactical.