I know that you can shoot .223 & 5.56 from either of these. Which is the better one to buy and why?
Also, what would be the advantages/disadvantages to 16", 18" & 20" barrels. I am building my first AR and was wondering about these couple of things.
Thanks

From everything I can find online there has been no definitive test done, but most seem to think it comes down to finding the right load for the gun regardless of chamber. I ordered mine in Wylde but saw several opinions that the 5.56 chamber is more forgiving and may handle a wider variety of ammunition without any feeding/extraction issues.

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.