Well the .222 Rem, which was developed as a varmit caliber became the .223 which was chosen as the military standard of the "assult rifle" AR15. what has always amazed me is, we shoot humans with woodchuck rounds.
barbra ann
You are going to have some nut thinking these two rounds interchange, they do not. The 223 cal. was developed for the AR15 , because Remington developed the 222 and to use it would have required paying Remington. Of the two the 222 is the better, mainly because the bolt action rifles it is chambered for have a different rifling twist than the one chambered for the 223. But in custom long guns all things are possible.