Guided by comments to the previous post (thanks!) I find that BATF just posted online a notice that its removal of M855 ammo from the exemption for AP ammo is a mistake. Sounds like the decision was made to remove M855, while allowing a sham comment period, and whichever team compiles the annual list of published ordinances was told about the decision but not told "but, 'officially,' this decision hasn't been made yet, so don't let it out."
Those responsible are probably down on their knees thanking the Almighty that this happened in early March. (Federal agencies do job evaluations after the end of the fiscal year, end of September. If you foul up in winter or early spring, you can hope that your supervisors forget about it by then. A disaster in September is a REAL disaster!)