I experimented with AA2200 and 55gr bullets several years ago. Ran ladders from book starting to max loads through several different AR's with barrel lengths of 12.5", 16", 18" and 20". Velocities were very fast, groups were very disappointing. More like shotgun patterns. Every barrel tested has easily been sub MOA with several other loads/powders and the same 55gr bullets. Gave up on AA2200 in .223. Hope you have better luck.