the original GE system. The optimum rate of fire was determined by Garwood to be around 3,200 rounds per minute (rpm). The M134G is being produced with this firing rate as well as 4,000 rpm and the previous standard 3,000 rpm rate. Garwood Industries made several other modifications to the 1960s Minigun design in order to meet modern-day military and ISO standards. This includes modifications to the drive motor, feeder and barrel clutch assembly. From 2015 to 2017 Garwood Industries CEO Tracy Garwood collaborated with firearms dealer Michael Fox and weapons smuggler Tyler Carlson to supply miniguns to Mexican drug cartels. Garwood submitted false paperwork to the ATF claiming that some M134G rotor housings had been destroyed when they were actually sold to the gun-running ring. In 2017 federal agents raided Fox's home and recovered two of the rotor housings that Garwood had reported destroyed. A number of the rotor housings were shipped to Mexico and a completed M134G using a reportedly destroyed rotor housing was recovered from a cartel by Mexican law enforcement. Garwood claimed he did not know that the intended buyers were Mexican cartels although he was aware that they were to be used for illegal activity. Design and variants The basic minigun is a six-barrel, air-cooled, and electrically driven rotary machine gun. The electric drive rotates the weapon within its housing, with a rotating firing pin assembly and rotary chamber. The minigun's multi-barrel design helps prevent overheating, but also serves other functions. Multiple barrels allow for a greater capacity for a high firing rate, since the serial process of firing, extraction, and loading is taking place in all barrels simultaneously. Thus, as one barrel fires, two others are in different stages of shell extraction and another three are being loaded. The minigun is composed of multiple closed-bolt rifle barrels arranged in a circular housing. The barrels are rotated by an external power source, usually electric, pneumatic, or hydraulic. Other rotating-barrel cannons are powered by the gas pressure or recoil energy of fired cartridges. A gas-operated variant, designated XM133, was also developed. While the weapon can feed from linked ammunition, it requires a delinking feeder to strip the links as the rounds are fed into the chambers. The original feeder unit was designated MAU-56/A, but has since been replaced by an improved MAU-201/A unit. The General Electric minigun is used in several branches of the U.S. military,