I went and bought an AR15...Bushmaster BFC15 today! Have to wait the usual 10 days in CA to pick it up. First non-Ruger purchase. Okay here is the first question for an AR newbie. It is 5.56/.223 Caliber....from what I read I can fire both 5.56 AND .223 ammo, but IF the barrel states .223 I cannot fire 5.56 rounds. Is that correct?