The order for the weapons came under a contract modification from the Naval Air Systems Command worth $7.8 million, the company said.
"General Dynamics has successfully produced the weapon system for the F/A-18 for more than 25 years," said Steve Elgin, vice president and general manager of armament systems for General Dynamics Armament and Technical Products.
"The M61A2 F/A-18 gun system continues to be relevant, affordable and extremely effective."
The M61A2 gun system is a six-barrel Gatling gun. It has a closed-loop rotary feed and can fire as many as 6,000 rounds a minute.
Additional details of the contract modification, as well as a delivery schedule, weren't disclosed but General Dynamics said the weapons would be produced at its facility in Saco, Maine.
Video of Victoria’s Secret models trying to 'twerk' hits Instagram
Workers accuse National Zoo of animal mismanagement