More than two dozen GAU-19/B systems will be delivered under the contract, as well as field support, spare parts and logistics.
General Dynamics said the GAU-19/B Gatling gun is a lighter variant of the .50-caliber, triple-barreled GAU-19/A used by the U.S. military.
"With about 250 systems currently in service, the GAU-19/A is a proven gun that is reliable in land, sea and air applications," said Steve Elgin, vice president and general manager of armament systems for General Dynamics Armament and Technical Products.
"The new GAU-19/B gun provides the same superior firepower as the GAU-19/A system in a significantly lighter package which easily integrates aboard existing platforms and expands the warfighters' performance envelope."
The guns ordered will be produced at the company's facility in Saco, Maine, delivered next month and installed on Army helicopters.