I once had a business law prof. who would argue that you could pass almost any law and use the interstate commerce rational. I asked him if that means that you could "legislate" communism, and he refused to answer my question and said that he wasn't going to fall into my trap. He was pretty pinko, but he actually agreed with me when I was the only one to say that the 2nd amendment pertained to individual rights and anti-oppressive government rational. He even brought up pre-WWII Germany.
I do think that we have to be careful with saying that gun laws don't work. It could play into a long term strategy of the anti's that since we can't control gun violence or guns, we have to get rid of guns, since pro-gun people even say that the laws don't work.