223 / 5.56mm
In every state I am familiar with its too small for deer hunting.It is considered too small for a humane kill.
I call it a rodent gun or something suitable for training kids and girls.
I would not want to be shot with one.
With that said, I’ve always thought .243 would be a good round for the AR15/M16 platform.
It’s got decent ballistics, provides a good bit more punch than .223, but is not as heavy as .308 so it’d be easier to carry more rounds on one’s person.
I know I am in the minority on this issue, and I also know that .243 is not a traditional/standard military and/or NATO-accepted round, but that’s my opinion and I’m sticking with it.
;-)