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. Adjustable blade front and fixed notch rear sights, front-mounted hammer, "MARK I MODEL B" marked on the left side, and a pair of smooth grips. Includes a MBAssociates Gyrojet box and five rounds of wadcutter ammunition.

Excellent, retaining 97% original black finish with some light handling marks, and some muzzle and high edge wear. Grips are very fine with dings and scratches. Mechanically excellent. Box is very good.