My accurate manual (circa 1994) lists a starting load of AA2230 for the .223 to be 23.4 under a 55 gr. pill and 26.0 to be max. Looks like you are right on track
My Lyman book lists 22.5 gr as starting and 25.0 as max. (Lyman 49th)
My Hornady book doesnt even list AA2230 in thier data for your exact bullet... (bummer)
The .223 round is one of my favorite cartridges. I find my best results with slow powders, especially if you load for an autoloader. My most accurate load is 25.5 gr IMR4895 under a 53 gr. sierra matchking. Its 3/4 MOA with a DPMS Lo Pro classic 16" bbl...