No. That is exactly wrong. The law is being made now to ban "armor piercing" ammo. The study creates new parameters to define ammo as "armor piercing." No new law is then necessary to ban additional types of ammunition. A bureaucrat simply adds new types of ammunition to the list of banned "armor piercing" ammo as defined by Congressional study and that's it.
Who will even say how heavy the body-armor used in the study has to be? No one will vote on a law about that.
I think that one's a no-brainer. They'll spec it for the body armor commonly used by LEOs, i.e., soft armor, designed to stop most pistol bullets.
IOW, all centerfire rifle ammunition will be prohibited. The USA will become a shotgun-only zone for big game hunting. That ought to scare the crap out of the complancent "they'll never come for my deer rifle" folks. No, they're not coming for your rifles, they're coming for your ammunition.
Good luck filling the freezer with venison when you're only allowed to load blanks into your Winchester.