It's a slide action handgun... hard to imagine any part of the design deserving "military secrets" protections when the devices themselves are the most widely available side arm in the US. Anyone can measure, 3D scan, weigh or otherwise capture the design to thousandths of an inch. For that matter, there are thousands of metal and gun smiths that could re-manufacture the design.
I could see the argument in the early 1900's, but today that's absolutely ridiculous on its face.