independent analysis of those testers' own published data shows that their conclusions were incorrectly calculated. The projectile's acceleration actually started out low and continually increased over the bullet's measured flight. Variants Gyrojet MkI Aside from a few Gyrojets tested by the United States military, most Gyrojets were sold on the commercial market starting in the mid-1960s. These were Mark I Gyrojets, which launched a .51 caliber rocket, and had ammunition that was costly to produce and buy. Gyrojet MkII In 1968, the U.S. Gun Control Act of 1968 created a new legal term, the destructive device. 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. Gyrojet assault rifle Assault rifle variant with M16-type ergonomics tested by the US Army. This variant had full auto capability and a removable grip inserted magazine. To increase ammo capacity, it is possible this rifle was chambered in the 6 mm caliber. Gyrojet carbine Came with a rifle type stock, pistol grip and scope. Gyrojet Derringer Derringer pistol with an upper barrel chambered for the Gyrojet round. Gyrojet flare launcher The Gyrojet principle was also examined for use in survival flare guns, and a similar idea was explored for a grenade launcher. The emergency-survival flare version (A/P25S-5A) was used for many years as a standard USAF issue item in survival kits, vests, and for forward operations signaling, with flares available in white, green, blue, and red. Known as the gyrojet flare, the A/P25S-5A came with a bandolier of seven flares and had an effective altitude of over . Its rounded-nose projectile was designed to ricochet through trees and clear an over canopy of branches. Gyrojet Lancejet An underwater firearm variant of the Gyrojet called the "Lancejet" was considered for use by the United States military. It was planned and tested but not adopted; the inaccuracy of the weapon eventually removed it from consideration. Gyrojet pepperbox pistol An experimental twelve-barrel Gyrojet pepperbox-type pistol was planned to be used, but was not, in the film version of You Only Live Twice. Gyrojet conversion gun The Studies and Observations Group (SOG) of the U.S. military in Vietnam in 1967 saw an opportunity to try