OK, guys with Federal AE .223 ammo with NATO brass and head stamp:
ATK, who owns Federal, also runs Lake City. They sometimes use LC brass in their cheaper lines ammo, this case AE. Why? LC brass is more heavily massed produced, making it cheaper, and it's available for them to use. Actually, AE ammo can have either Federal marked brass or LC, just depends on what they want to use.
Don't worry, the AE ammo in .223 boxes with LC brass is loaded to .223 specs.
Also note: XM193 is loaded with LC brass with a NATO headstamp, there is no NATO spec for 55gr 5.56 (only US' M193 spec); only 62gr 5.56. It's just cheaper to use M855 brass that's available.
Win 5.56 Q3131 is the same way, it can be loaded in Win's M855 leftover brass with NATO stamp or WCC comerical brass. Either way it's loaded to M193 specs.
One thing's for sure, if it's marked 5.56 it's loaded to a higher pressure than .223. Will it KB a modern rifle? Probably not. Can it cause extraction issues? Yes.