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.

The space age-looking carbines and an assault rifle variant with a removable grip-inserted magazine were tested by the US Army, where they proved to have problems.

Working for free out of his Livermore Aerospace Plastics Lab, Minchakievich requested six more months to perfect an accurate projectile, and make the Gyrojet more famous than the Colt Peacemaker.

Minchakievich even attempted a marketing strategy by enlisting the help of Gene Roddenberry in using the pistol on Star Trek.

Although Roddenberry loved the Gyrojet, he wanted a "ray gun" and not a pistol that merely shot a rocket projectile, no matter how advanced for the twentieth century.

Spin stabilization of the Gyrojet was provided by angling the four tiny rocket ports rather than by forcing the projectile through a rifled barrel.

[9] However, in later tests accuracy proved very poor; the difference seems to have been due to a manufacturing flaw in later production runs which partially blocked one of the exhaust ports, creating asymmetrical thrust that caused the projectile to corkscrew through the air.

[10] About one thousand of the "Rocketeer" model pistols were produced; a few saw service in the Vietnam War and were featured in the James Bond book and movie You Only Live Twice, the Matt Helm film Murderers' Row, and The Man from U.N.C.L.E.

At about the same general size as the Colt M1911, the Gyrojet was considerably lighter at only 22 ounces (625 g), as the structure was mostly made of Zamac, a zinc alloy.

The pistol lacked a removable magazine; rounds had to be pushed down from the open "bolt" and then held in place by quickly sliding a cover over them on the top of the gun.

Tests in 2003 claimed that the acceleration, rather than being constant, started at a high value and decreased, leading to velocities at close range which were not as low as expected, about 100 ft/s (30 m/s) at 1 foot (30 cm) instead of the calculated 20 ft/s (6.1 m/s).

Under the new law, any weapon firing an explosive-filled projectile over a half-inch in diameter was considered a destructive device and required paying a tax and obtaining a license.

The registration process was changed several years later, but in the interim, MBA created the legal Gyrojet Mark II, firing a .49 caliber rocket.

The Gyrojet principle was also examined for use in survival flare guns, and a similar idea was explored for a grenade launcher.

In one test, a rocket round punched through an old truck door and into a water-filled 55-gallon drum, almost exiting its opposite side.