A product of the 1960s, the Mark I Gyrojet uses a 13mm solid fuel rocket in place of a standard cartridge. As the rocket does not need a solid chamber or extractor equipment, the entire pistol can be greatly simplified and made from lightweight materials. Fixed blade front and fixed notch rear sights, front-mounted hammer, "EXPERIMENTAL/MARK I" marked on the left side, and a pair of smooth grips. With a hardwood MBA display case and eleven dummy rounds of Gyrojet ammunition.

Excellent, retaining 99% plus original black finish with limited handling marks and some wear on the external small components. Mechanically excellent. Case is fine with storage and handling marks with some high edge wear on the interior.