whereas the 1994 ban applied to a rifle or shotgun the "pistol grip" of which "protrudes conspicuously beneath the action of the weapon," the new bill would drastically expand the definition to include any "grip . . . or any other characteristic that can function as a grip." Also, the new bill adds "forward grip" to the list of prohibiting features for rifles, defining it as "a grip located forward of the trigger that functions as a pistol grip." Read literally and in conjunction with the reduction from two features to one, the new language would apply to every detachable-magazine semi-automatic rifle. At a minimum, it would, for example, ban all models of the AR-15, even those developed for compliance with California's highly restrictive ban.

(http://www.nraila.org/legislation/federal-legislation/2013/stop-the-gun-ban.aspx)