In 1955, Rock Island Arsenal's Research and Development Division began designing a towed, helicopter-transportable launcher for the 318MM Little John rocket. The project went through several phases. The Little John rocket system had three component parts: The rocket, the launcher, and the trailer. This system had an XM80 rocket launcher, and an XM505 two-wheel trailer. Both of these components are serial number 3, and were manufactured at Rock Island Arsenal between 1959 and 1960.

The Second Nuclear Missile

Developed to complement the larger Honest John, the MGR-3 Little John was a near-field rocket system capable of deploying atomic or high-explosive payloads at close range. The system was developed at Redstone Arsenal beginning in 1955, with the first launch of the XM47 occurring in June 1956. This first production rocket was stabilized in flight by the spinning of the rocket body. The final production variant of the rocket, the XM51, was stabilized from launch by initializing a spin on the rail of the launcher.

The rocket system was developed to be light enough to be deployed into a vast assortment of environments. This included the ability to be transported with ease by helicopters. Rock Island Arsenal was tasked with the development of a light-weight launching system, and the accompanying trailer that could be carried by helicopter. Designated the XM80 launcher, the system weighed considerably less than the original XM34 launcher. It was also more compact to allow easier navigation of the carrying aircraft. Neither the XM80 nor the XM505 launcher or trailer were ever deployed.

The first XM51 rocket system was delivered to the field in 1961, with the bulk being sent to Okinawa, Japan, where they were maintained by the 1st Missile Battalion. With the introduction of smaller, lighter, and more accurate missile systems, the Army began to decommission and retire the Little John in 1967. By 1970, all of the remaining missiles had been decommissioned and removed from the Army inventory.