The Slidefire is as far as I know the closest way to fire a US legal-semi-only AR in "auto mode." There really is no point, personal defense is something of a joke of an excuse since not many people carry AR15's every day for that purpose (with of course the exception of the zombie apocalypse or a breakdown of the law enforcement system like after Katrina). But I will say firing automatic weapons is something of a dream for many, and a very expensive hobby for some. It is awesome, and there is just no comparison against semi only weapons. Slidefire is great for rich people who dump inordinate amounts of money into ammo stockpiles, and a shovel to dig a money pit for average peeps.