It's not enough to make gun buyers undergo background checks. A would-be killer's background may be spotless, and those whose backgrounds aren't will findother ways to get firearms, including theft. Banning the manufacture of certain firearms and magazines won't work either, because millions of them already exist, and no one proposes confiscation — if for no other reason than that it would be a mission impossible. So what should Congress do? If it were really serious, writes Sheldon Richman, it would pass a law forthwith requiring every gun buyer to declare whether or not he intends to commit a crime with the gun.