Ok this is a dumb question and i am pretty shore i know the answer already but. My buddy went out and bought a cheap ar15 "an olympic i think its spelled" and his salesman told him he can shoot either .223 or 5.56 now it is chambered for .223.
now when i bought my dpms ar15 chambered for .223 i was told not to mix the ammo that 5.56 wouldnt work in a .223
so who is correct here?

