To those who are supporting mandatory buy backs, How are you going to enforce it? If the government doesn't know I have it how will they know if I sell it? How will the government know if I have one of those weapons and that I haven't sold it back to them? (which is incorrect as they didn't sell it to me to start with so they can't buy it back). What they are going to do is use my tax dollars to buy something from me at heavily discounted prices that I paid for at normal prices and paid taxes on. I do believe there are a couple of amendments to the constitution that say "You can't do that!"