Green tip ammo was about to be made illegal by the BATFE - it didn’t take an act of Congress for this to *almost* happen. In fact, it wasn’t until enough folks began writing their Congressman to complain and they started asking questions, that BATFE backed off their “redefinition” of what constituted “sporting use” for that type of ammunition. How soon we forget...
But it was not put into effect. You say because folks began writing their Congressman others say because the ATF realized they already had an exemption on the books for green tips and couldn't do so according to the law. Did they try to pull a fast one, perhaps, but they were called out on it, just as they would be in this case if they try to redefine a slide stock as causing a semi auto to act like a machine gun.