Those who argue that all guns should be banned will never in their life time see it happen in the USA. I know the adage of avoiding the word "never". However, there are 100's and 100's of millions of guns in the hands of over a hundred million Americans. Guns are very easy to purchase legally in this country. You can walk into a Walmart that sales gun and walk out with a rifle that holds a 30 round clip (depending on location) capable of firing a .223 round as fast as you can pull a trigger. You just have to fill out 4473 form and a background check. Most locations only have to keep the 4473 for twenty years and after that records go bye bye. Most are paper base and not kept in digital format.
So how exactly do you plan on disarming millions of people? Keep in mind there is no national gun registry.
A more realistic route is some of the suggestions Simon gave.