Because those don't actually do anything. A high capacity magazine is less sophisticated than a beer can and we already have two centuries of supply in circulation, and reloading takes about two seconds. Assault weapons are used in mass killings only a sixth as often as a cigarette lighter, and are not as effective at killing people. Post Heller, a gun ban is clearly unconstitutional, and given the UK's example, would just mean that only
violent criminals and the mentally ill would have guns.