As soon as it was airborne, the drone flying inside West Point crashed to the ground at the feet of Secretary of Defense Ash Carter. The soldier responsible for the drone's demise gently lowered the weapon, no smoke wafting from its barrel, not even a sound made with the shot.
Built by the Army Cyber Institute at West Point, the rifle was demonstrated last fall at the Association of the United States Army exposition in Washington, DC. Unlike pretty much every other variety of gun, this rifle doesn't shoot any projectiles. Instead, it uses an antenna, wi-fi radio, a cheap Raspberry Pi computer, and a known weakness in the Parrot quadcopter to jam the controls of the drone, sending it crashing to the ground. The design could presumably be tuned to take down other drone brands as well.
This version was built by Captain Brent Chapman for the the Army Cyber Institute at West Point, and cost just $150 in parts. That makes it exactly the sort of weapon, built from existing information and commercial technology, that DARPA's looking for in a new program. Success breeds imitation, or perhaps because design converges, as soon as Chapman debuted his rifle in October, another version came from defense contractor Battelle.
As the anti-drone arms race continues, expect to see many more devices like this emerge. $150 is cheaper than most commercial drones, and way cheaper than many more elaborate anti-drone weapons. Plus, no eagles required.