i'll throw my weight behind what everyone else is saying. get what you can, now.
the best I've done recently is I loaded around 700 .223 rounds. about 300 of which were regular FMJ, then I couldn't find anymore 55gr FMJ so I paid a little more for what was available. some 64gr SPBT's and some 69gr HPBT's. not my first choice, and trust me, I'd rather load cheap shit, but it's what I could get, and the diameter matches my barrel.. so....
back when we had a choice, this thread could have flourished with discussion. but now, just get whatever the fuck you can get... IF you can get it.