The real purpose of these types of laws/legislation is to limit what people can use/make for ammunition for firearms. Basically, it's a backdoor way to make owning a firearm so expensive people won't have one. In other words, a way to disarm the populace. Once that's done, a lot of other government takeover stuff can happen, just see European countries and what goes on there related to healthcare, etc. The average joe basically has no rights, not even to protect himself, his home or family.
Legislation that's "good for the environment" often has a net result of less freedom for "common man" who apparently can't think for himself. Look in the mirror if you want to see who that "common man" is.
With as much government takeover of business/banking/healthcare is going on now, if we don't vote the election this fall, we may not be able to vote for much longer. I hope I'm wrong on this one. Regardless, this country doesn't look anything like the one I grew up in back in the 70's. Much, much less freedoms now, much, much more government regulation and control.