Follow up to my reply / post on page 2
One of my boys did shoot a deer with the .223 out of a AR.
The doe was just 15 yards away and went only 20 yards after the shot.
Rifle was a Windham SRC with a Bushnell TRS-25 red-dot.
He used my handload, a 60 gr. Nosler Partition chronographed at 2,807 fps from a 16'' barrel.
The bullet made small entry and exit holes, but did significant damage to both lungs.
Criminals and psychos are mobile and my show up in "good" areas unexpectedly, carry accordingly.
Carry the gun you would you would prefer to defend your life with, in the off chance you have to.