I know Hornady makes a 75 grain hollow point match and a 68 grain game. Sierra has a 90 grain bullet. I can;timagine it would stabilize in a slower than 1:8 twist, I looked at some load data and it is pretty much 1:7 twist for the real heavies. An 80 grain bullet at 25-2600 fps definitely puts a new complexion on the 223.