Years ago my friend had a 9" 300 whisper barrel for his contender, and it was capable of 1/2 moa with 220gr mk loaded supbsonic though it was not supressed. Not just a wild claim from a buddy, I shot a 3 shot 1 ragged hole group with it with my hands numb as the temps were in the teens. Now if a break open handgun is capable of that accuracy, there is no reason an AR can't achieve the same accuracy.
I don't want to start the 300 whisper vs 300 AAC blackout argument, but you might want to consider SSK industries.
As far as not having a long wait, if your goal is top accuracy find who does the best work and wait as long as it takes.
