`(L) A semiautomatic rifle or shotgun originally designed for military or law enforcement use, or a firearm based on the design of such a firearm, that is not particularly suitable for sporting purposes, as determined by the Attorney General. In making the determination, there shall be a rebuttable presumption that a firearm procured for use by the United States military or any Federal law enforcement agency is not particularly suitable for sporting purposes, and a firearm shall not be determined to be particularly suitable for sporting purposes solely because the firearm is suitable for use in a sporting event.'.