Texas Arms Model-351 Gyrojet Pistol

Texas Arms Model-351 Gyrojet Pistol aka (Texas Arms 351 Gryojet Pistol in Deep Space) is gryojet pistol. Developed as a lightweight gyrojet weapon along the lines of the earlier Mark II models of the 20th century, the 351 pistol fires a 9mm rocket round. Range is 3x that of a normal pistol in vacuum. The 351 is a commonly used military firearm, particularly on Luna, but is rarely seen Earth-side.

Source

 * Deep Space, pg.58
 * Blackhand's Street Weapons, pg.13