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 "Rocketeer" box.

Excellent, retaining 98% original black finish with a few light handling marks, and minimal high edge wear. Grips are also excellent with limited handling marks. Mechanically excellent. Box is very good with storage and handling marks and water staining.