If you want higher odds of getting an accurate AR go .223 chamber or Wylde. I personally would not buy a 5.56 chamber unless it was for specific reason that right now I cannot think of.
Of course I am also 98% of the time shooting reloads but have no qualms about shooting 5.56 pressure loads in my match chamber .223.
Also I have seen very accurate 5.56 chambered AR's but when I put a custom barrel on I certainly don't ask for a 5.56 chamber..... I get the ..223 Rem.
"Anyone taking up handloading necessarily plays with unknown factors and takes chances. But so does anyone who drives a car,goes to a cocktail party,eats in a restaurant,or gets married."
Jack O'Connor 1963