Sounds like you're deep into it with that AR. Sure are fun ain't they? I went a bit different route than most of the guys here for a predator hunting AR. I wanted as much downrange performance as i could get out of it so had mine chambered in 223AI, with a 9-twist 26" Hart[shoulda' been an 8-T though]. I also scrounged up a couple of the old DPMS VLD magazines they used to make so i could shoot 75 A-Maxes efficiently in the magazine. Worked great. My best load gave me .75 MOA accuracy at 2940ish fps. I also tried the 65 JLK Low Drag with fantastic long-range accuracy, but have moved away from that bullet for hunting and now use the 65 Sierra GK for most of my AR hunting these days, as i feel it gives me the best ALL-AROUND performance at both short and long-range out of a 22 cal. AR.
IMO the longest practical range for shooting/killing predators efficiently is 500-600 yds. with a 22 caliber AR. That's the best i've been able to accomplish anyways with any degree of consistency/accuracy in the field on basically a 6" live target.