As if the confusion regarding the .223 vs 5.56 chambers wasn’t enough, there is a third possibility in the mix, that is being used by at least one major manufacturer. The .223 Wylde chamber is a modified SAAMI-spec .223 chamber that allows for the safe use of 5.56 NATO rounds, but maintains tighter tolerances for better accuracy.
The Armalite Eagle-15 I picked up last June is chambered in .223 Wylde. That's what sold me on it.
