Melvin M. Johnson, Jr. was born in Boston, Massachusetts, on August 9, 1909, and graduated from Harvard Law School in 1934. He was a successful lawyer and taught for a short time at Harvard Law School. However, his life-long interest in firearms soon led him down a different path.
Johnson assisted local weapons designer, Franklin Young, in designing a rifle that, while not accepted by the Ordnance Department, motivated him to develop his own rifle. As a Marine Corps Reserve officer, he had observed early trials of the Garand rifle at the Springfield Armory and was convinced he could design a better one. Although Johnson's rifle did not compete successfully with the Garand design and the Army ultimately adopted the Garand as the famous M1 rifle of World War II, the controversial trials were helpful in identifying flaws in the M1's gas operating system that led to improvements in the final design.
Undeterred, Johnson put his rifle and an excellent light machinegun he had designed into production. Although the Dutch Army placed a large order for these weapons to equip its forces in the East Indies, the Japanese overran this Dutch territory during World War II before the weapons could be delivered. However, the US Marines were able to take delivery of many of these weapons to equip their Parachute and Raider Battalions, and the light weight and high rate-of-fire made Johnson's machinegun very popular.
Johnson also became involved in a series of other projects during World War II. He developed sub-caliber trainers for .30 and .50 caliber machineguns, refurbished World War I vintage Enfield rifles with new barrels, developed an 81mm shoulder-fired recoilless weapon, designed flash hiders, reduced erosion in machineguns using barrel liners, and redesigned chambers. Likewise, in the years following World War II, he was instrumental in developing an electrically-operated Gatling gun that led to the Vulcan and mini-gun weapons.
In the 1950's and early 1960's, Johnson was widely recognized as a weapons inventor and designer and served as a consultant to the Assistant Secretary of Defense for Research and Engineering, the Chairman on Aircraft Armament, the Chairman of the Munitions Board, the Historical Evaluation Research Organization of the Combat Developments Command, and numerous civilian industries. He was also well known as a promoter and spokesman for effective small arms, authoring or co-authoring 8 books and some 80 articles on weapons, tactics, and marksmanship.
In 1949, Johnson transferred from the Marine Corps Reserve to the Army Reserve with an appointment as Colonel in the Ordnance Corps, a rank he held until retirement from the Army Reserve in 1961. While actively pursuing the development of a carbine for use in counterinsurgency warfare, Johnson suffered a heart attack and died in 1965.