Was at Gander Mountain the other day checkin out some knives... decided to go look at some guns they had out. Looked at a couple of AR models. Just saw one that was chambered for 5.56... I'm just wondering if one can even buy 5.56 anywhere? I was under the impression that it was pretty much the same thing as .223. What is the difference? And even there, wouldn't one be better off with .223 as it seems like it would be easier to find and buy? I guess just wondering what is so different about 5.56 from .223?