I use H335. I've been told it's dirty and temp sensitive, but it's the most accurate powder in my carbine length AR's.
Same here. I haven't owned a .223 in quite a while (blush) but my Ruger 77 Mk II RL and my Rem 700 20" heavy barrel both shot best with H335 and 50s, 52s, and 55s.
It might be temperature sensitive but I sure never had any issues with it.
Another favorite was AA2230 under a 45 grain Hornady pointy .224 hornet.
Tom
