The MGR-1 Honest John rocket was the first nuclear-capable surface-to-surface rocket in the United States arsenal. Originally designated Artillery Rocket XM31, the first unit was tested on 29 June 1951, with the first production rounds delivered in January 1953. Its designation was changed to M31 in September 1953. The first Army units received their rockets by year's end and Honest John battalions were deployed in Europe in early 1954. Alternatively, the rocket was capable of carrying an ordinary high-explosive warhead weighing . History and development Developed at Redstone Arsenal, Alabama, the Honest John was a large but simple fin-stabilized, unguided artillery rocket weighing in its initial M31 nuclear-armed version. Mounted on the back of a truck, the rocket was aimed in much the same way as a cannon and then fired up an elevated ramp, igniting four small spin rockets as it cleared the end of the ramp. The M31 had a range of with a 20 kiloton nuclear warhead and was also capable of carrying a conventional warhead. The M31 system included a truck-mounted, unguided, solid-fueled rocket transported in three separate parts. The Honest John was assembled in the field before launch, mounted on an M289 launcher, and aimed and fired in about 5 minutes. The rocket was originally outfitted with a W7 nuclear warhead, with a variable yield of up to ; in 1959, a W31 warhead with three variants was deployed with yields of 2, 10 or 30 kt (8.4, 41.8 or 125.5 TJ). There was a W31 variant of used exclusively for the Nike Hercules anti-aircraft system. The M31 had a range between . Early tests exhibited more scatter on target than was acceptable when carrying conventional payloads. Development of an upgraded Honest John, M50, was undertaken to improve accuracy and extend range. The size of the fins was greatly reduced to eliminate weathercocking. Increased spin was applied to restore the positive stability margin that was lost when fin size was reduced. The improved M50, with the smaller fins and more "rifling", had a maximum range of 30+ miles with a scatter on target of only , demonstrating an accuracy approaching that of tube artillery. The Honest John was manufactured by the Douglas Aircraft Company of Santa Monica, California. In the 1960s, sarin nerve gas cluster munitions were also available, designed to be interchangeable for use with either the Honest John or MGM-5 Corporal. Initially the