Officials at the Lawrence Livermore National Laboratory have added a new weapon to their armory: a high-powered machine gun that can fire more than 50 rounds a second.

The weapon, unveiled Thursday, is a six-barrel Gatling gun called the Dillon Aero M134D. An undisclosed number of the guns will be mounted on vehicles and elsewhere at the lab.

"What we want to do is equip our protective force with the capability that will leave no doubt about the outcome," said Linton Brooks, head of the National Nuclear Security Administration.

Lab critics questioned the wisdom of putting such a powerful gun at the lab, which is across the street from suburban homes. They say the real problem is that the lab site, which is relatively small at 1 square mile, is not a good place for nuclear materials.

State and local officials have criticized the federal government for not providing more Homeland Defense funding to local police and emergency departments...The National Nuclear Security Administration defended Sandia's efforts to obtain a more capable grenade launcher but agreed the lab should have sought an American-made product first.