Gyrojet

Gyrojet
The Gyrojet carbine and rifle at the National Firearms Museum
Type	Small arms (rocket launcher)
Place of origin	United States
Service history
Wars	Vietnam War
Production history
Designer	Robert Mainhardt Art Biehl
Manufacturer	MBAssociates
Variants	See Variants
Specifications
Mass	0.88 lb (0.40 kg)
Length	10.88 in (27.6 cm)
Barrel length	5 in (13 cm)
Cartridge	Mark I: 13 mm rocket Mark II: 12 mm rocket
Caliber	Mark I: .51 caliber Mark II: .49 caliber
Action	Blowback
Rate of fire	60 RPM Select fire (assault rifle variant)
Muzzle velocity	Very low, but increasing over trajectory to about 1250 fps
Effective firing range	55 yards (50 m)
Feed system	6-round internal box magazine (main variants)
Sights	Iron sights

The Gyrojet is a family of unique firearms developed in the 1960s named for the method of gyroscopically stabilizing its projectiles. Rather than inert bullets, Gyrojets fire small rockets called Microjets which have little recoil and do not require a heavy barrel or chamber to resist the pressure of the combustion gases. Velocity on leaving the tube was very low, but increased to around 1,250 feet per second (380 m/s) at 30 feet (9.1 m). The result is a very lightweight and transportable weapon.^[1]

Long out of production, today they are a coveted collector's item with prices for even the most common model ranging above $1,000. They are rarely fired; ammunition, when available at all, can cost over $200 per round.^[2]