The contract modification adds $34.8 million to a previous deal with the Illinois-based Army Field Support Command worth approximately $116 million. Under the contract, General Dynamics will continue overseeing a program to demilitarize obsolete and excess ammunition.

The ammunition demilitarization program includes the recycling of six types of ammunition that can no longer be used by the U.S. military. As part of the program, the ammunition materials that can be used again are recovered and the rest is recycled.

"General Dynamics has a long history of performing ammunition demilitarization for the Department of Defense," Dean Bartles, General Dynamics Ordnance and Tactical Systems vice president and general manager of large caliber ammunition, said in a statement.

"Under this contract, we manage the environmentally safe thermal treatment of excess and obsolete ammunition."