I just put together a 12 twist 26" 223AI on a savage action. It's a purpose built prairie dog slayer. While researching, some guys mentioned the 223AI just seems more efficient. I would tend to agree with this statement in my limited experience so far. I just threw together a fireforming load with H335 and 40gr vmax bullets. It shot less than 1/2" at 100yds in horrible conditions. And in a pinch, you can shoot vanilla 223 in a properly setup gun. Nothing not to like so for in my opinion.