.223 isn't a military cartridge. 5.56x45mm NATO is a military cartridge. .308 isn't a military cartridge, 7.62x51mm NATO is a military cartridge.
The whole idea is fucking stupid anyways, since god only knows how many popular, common cartridges have been used by the military at some point. On top of that, the politically motivated could just direct military procurement to outlaw every new replacement round.
What? The military made a spec for a rifle cambered in .247, gave it a designation, and had a single unit produced, and kept for special purposes? Fuck you for not having 1000.00 laying around to start reloading.