Gyrojets are a family of unique firearms named for the method of gyroscopically stabilizing its projectiles. Firing small rockets rather than inert bullets, they have little recoil and doesn't require a heavy barrel to resist the pressure of the combustion gases. Velocity on leaving the tube is very low, but increases to around 400 m/s at 9 meters. The result is a very lightweight weapon with excellent ballistics.
Gyrojets come in pistol, carbine, rifle and machine-gun versions.
Behind the scenes
Gyrojets are very similar to Bolter Weapons known from the Warhammer 40,000 universe.