With 223, my personal opinion is to go extreme. Either really short or really long. I had a 16.5 inch H&R that was just the bee knees. I could still get 3000fps from 55gr bullets. 65 grainers got just under 2900 with handloads. Also had a HBar 24" AR for about 3 months. Never shot that barrel through the chrono, but dang was it accurate. It was very unwieldy. One of those things I that was great on paper and at the bench, but mostly sucked in real life. I actually did a lot of deer hunting with the 16.5 inch gun. 22 cal is legal in my state. Barnes bullets turned lungs to pudding.

So, if you want short, go short with a muzzle break or flash hider. It'd be super cool.