You are correct. Of course the EPA is planning to "regulate" lead used in ammo too. Then there is the legislation that will require each bullet sold to have a laser etched serial number on the back end of the slug. This will cost much more and further deter law abiding citizens from buying more. This does nothing to deter criminals who steal their ammo.
Our only hope is that there are enough reasonable Constitution loving Senators to refuse ratification of the UN treaty. We should never allow the UN to regulate anything in the US........we have a Constitution to protect us from that sort of stuff. But the Constitution is only powerful if we USE it and embrace it.