FutureWeapons goes big on guns starting with the rapid-fire cannon that's fast becoming a huge hit with the U.S. armed forces. Next up, Mack takes a helicopter ride where he unleashes a firestorm with the lightweight Dillon Aero Gatling gun. On an Arizona firing range, he tests a new multi-caliber combat weapon that's lighter and tougher than any other weapon in its class. In the finale, Mack checks out a new breed of personal defense weapons that have the stopping power -- and amazingly, the accuracy -- of much bigger weapons.