(6) The manufacture, transport, testing, delivery, transfer or sale, and all lawful commercial or experimental activities necessary thereto, of rifles, shotguns, and weapons made from rifles or shotguns, or ammunition for such rifles, shotguns or weapons, where engaged in by a person operating as a contractor or subcontractor pursuant to a contract or subcontract for the development and supply of such rifles, shotguns, weapons or ammunition to the United States government or any branch of the Armed Forces of the United States, when such activities are necessary and incident to fulfilling the terms of such contract.
The exemption granted under this subdivision (c)(6) shall also apply to any authorized agent of any such contractor or subcontractor who is operating within the scope of his employment, where such activities involving such weapon, weapons or ammunition are necessary and incident to fulfilling the terms of such contract.