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 of the barrel rib with serial number marked on the bottom, and a pair of smooth grips. The changed position of manufacturer and model markings are commonly seen on the early Model B pistols which were typically engraved with the original owner's name before leaving the factory. Includes seven live rounds of gyrojet rocket ammunition and operating instructions.

Excellent overall, retaining 99% plus original blue finish with limited handling marks and a small spot of protective coating on a small scratch on the left side. Mechanically excellent.