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 presentation case, medallion, three Gyro jet brochures, and 11 rounds of gyrojet ammunition (5 round nose and 6 semi-wadcutters).

Excellent, retaining 98% plus original black finish with a few light handling marks and high edge wear on the rear sight. Mechanically excellent. Case is very fine.