FWIW I would not waste the time on the 222 unless you have brass/dies etc..... 223 is plenty accurate and extremely versatile.
Accuracy-- easy to get half inch at 100 and under given right loads. My best accuracy tests reveal that even in an AR the 223 will shoot 10 shot groups around an inch at 300 with the right ammo and best 5 shot groups at 600 will net 1-2 inch groups at 600. I think you would be happy, assuming the barreling job is correct.
Before you start, thing what distance you are going to be shooting vs the twist rate. My 6.5 twists shoot up to 90s and down to 52s.... Not advising that twist, simply I prefer to err on the stable side and it usually doesn't hurt the shorter bullets much if any. That being said if you want to spin out 40s only, consider that twist and make sure your chamber is well thought out for what you are going to do.
Jeff
