It also says "made to mil-specs fro M-16 Rifles"
If it says it's mil-spec, why don't you believe it.......
But it says ".223 remington" on it. I know it's loaded to 5.56 spec, it is also the exact ammo that is in the yellow norinco box, I'm not the one that is concerned about it. The OP is, I've already said I don't have any problems shooting 5.56 in a .223 chambered rifle. All 4 of those boxes of ammo have been shot through my savage rifle without issues.