Re: AR ammo
I personally shoot Tula Russian in my AR. I have also bought the Herter's, which I believe is the same manufacturer. I had one case get stuck in the chamber out of a few hundred rounds. No other issues have surfaced yet. I don't reload, so steel case makes sense for me.
For brass-cased ammo, I hear that many Wal-Marts will have 420 rounds of Federal 62gr FMJ in an ammo can at good prices. Have't seen that personally.
Another choice may be to check out Cat Ammo. they do bulk re-manufactured rounds. I think they may be based in PA. Haven't checked them out yet.
Aim Surplus usually has decent deals. I can't recommend Palmetto State Armory anymore, because they never seem to have anything in stock.