The names of firearms designers such as John Moses Browning, Mikhail Kalashnikov and Eugene Morrison Stoner are synonymous with iconic firearms. Stoner was a prolific firearms designer who was responsible for the AR-7 U.S. Air Force survival rifle, the AR-10 rifle, the SR-25, and, of course, the AR-15 and M16 rifles.
Stoner was born in Gosport, Indiana, and eventually moved to Long Beach, California. Since there was no money for him for college during the Depression, he took a job at Vega Aircraft Company, the forerunner of the Lockheed Corporation, installing armament systems. When World War II broke out, Stoner enlisted in the Marine Corps and became an Aviation Ordnance man, serving in China and the South Pacific.
After the war, Stoner began work at the Whitaker Aircraft Equipment Company as a machinist, rising to the position of design engineer. In 1954, Stoner took a position as Chief Engineer with the ArmaLite Division of the Fairchild Engine and Airplane Corporation and developed several firearm prototypes, including the AR-7, the groundbreaking AR-10, and the AR-15 and M16 rifle.
A New Era
In the mid-50s, the U.S. Military was looking for a replacement for the M1 Garand, and Stoner submitted his AR-10 design. The AR-10 was extremely unconventional for its time, constructed using fiberglass and lightweight aluminum alloys, employing an eight-lug rotary bolt, and a direct gas impingement system.
The patent for this gas-operated system was filed in 1956 for use in the AR-10, which was later developed into the AR-15 and M16 rifles. In U.S. patent 2,951,424, Stoner states: ″This invention is a true expanding gas system instead of the conventional impinging gas system.″
In 1956, the AR-10 competed against both the M14 rifle and the FAL rifle to replace the M1 Garand and lost, but Stoner’s gas system eventually went on to become the new standard with the AR-15/M-16 family of rifles.
In 1960, Colt Firearms purchased the rights to the AR design, and Stoner became a consultant. While there, Stoner conceived a modular rifle that could be configured with different subassemblies for the mission at hand. Stoner took the idea to defense contractor Cadillac Gage and brought with him Jim Sullivan and Bob Fremont, who had helped Stoner develop the AR-15.
Stoner 63 Modular Weapon System
The Stoner 63 Modular Weapons System was a unique concept that enabled the shooter to configure the rifle into several different weapon systems using a common multi-use receiver. Using interchangeable components, the long stroke piston-operated Stoner could be set up as six different and unique weapon systems. Also, the Stoner 63 used a stamped sheet metal receiver. It was a simple and robust weapon that could be produced affordably in large quantities.
The first Stoner design was the Model 62 chambered in 7.62×51 NATO ammunition. Later in 1962, the Stoner was chambered in 5.56x45mm to reduce weight and was renamed the Stoner 63. Developed with military sales in mind, the Stoner 63 caught the interest of the U.S. Marine Corps and the Defense Advanced Research Projects Agency (DARPA). In August 1963, both were given a demonstration at Quantico, Virginia, and prototypes were ordered.
As noted, the Stoner Weapons System was designed with simplicity in mind. It uses sheet-metal stampings for ruggedness and reinforced plastic or wood buttstocks and forends. The basic component group could be mass-produced. Any interchangeable assemblies are 81.3% common to two or more components. An operator needs only one training class to learn how to use, maintain, and repair six different weapon systems. The Stoner touts its use of only 5.56mm ammunition, which simplifies the ammunition supply chain.
Modularly Designed
Due to its design, six separate arms could be built from the basic component group. These include an assault rifle, a carbine, a fixed machine gun, a belt-fed light machine gun, a magazine-fed light machine gun, and a medium machine gun.
Any firearm in the Stoner weapons system is a selected group of assemblies from the 16 component assemblies, which include the basic component group, the machine gun barrel assembly, the folding buttstock, the bipod, the Stoner or M2 tripod with cradle adapter, the belt feed group, the buttstock, the machine gun rear sight, the magazine, the machine gun forearm, the magazine adapter and forearm assembly, rear side assembly for the rifle or carbine, the solenoid and trigger linkage, the rifle barrel assembly, the carbine barrel assembly, and the magazine adapter for the machine gun.
The Stoner light machine gun can be converted from a rifle into a belt-fed machine gun, or into a magazine-fed machine gun with the magazine inserted on the top (similar to a Bren) quickly and with just a few tools.
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The Stoner 63 was fed from a proprietary 30-round magazine or from belts in a box or drum. The machine gun barrel could be removed and replaced while hot using the handle alone, without a glove or any other assistance.
The Stoner was also known for its light weight. Since it was chambered for the 5.56mm, the Stoner machine gun configuration weighed about half as much as the M60 machine gun, allowing gunners to carry much more ammo.
The Operating System
As noted, the Stoner operating system was a piston-driven, air-cooled system that fires from a closed bolt except in machine gun mode, when it fires from an open bolt to improve cooling and prevent cook-offs.
The Stoner has a rotary bolt locking system with seven symmetrical locking lugs that engage the recesses in the barrel extension. When fired, the propellant gases from the cartridge are vented through a gas port into a gas cylinder where they drive the piston and bolt carrier rearward.
Incorporated into the bolt carrier piston assembly is an anti-bounce device consisting of a 4” carbide rod that reduces bolt bounce to prevent firing out of battery during closed bolt operation in the rifle and carbine configurations.
Stoner 63A
Stoner was always improving his design, and in 1966, with the help of user feedback, he introduced the Model 63A. This revised version fixed some of the original’s issues, including a stronger polycarbonate stock and forearm, a redesigned cocking handle, an upgraded feed cover and feed tray, a pair of spring-loaded ejection port covers, and a stainless steel gas tube for corrosion resistance.
One of the issues with the Stoner design was high cyclic rates. When the Stoner was cold, it fired at around 650 rounds per minute. When it was hot, the rate of fire increased to as much as 1,100 rounds per minute! That cyclic rate caused the rifle’s mechanical functions to break down, leading to malfunctions and link separations. The fix for that issue was the addition of a rate regulator, similar to the M60 installed in the buttstock, which limited the rate of fire to 800 rounds per minute.
The End Draws Near
According to Jim Sullivan, Stoner’s colleague, the Stoner Weapon System’s lack of acceptance may have been political. As Sullivan recalls, “I left … in 1965 after the Marines had tested the Stoner 63, ordered 300,000 and been shot down by the Senate funding committee which decided that the Marines should use what the Army uses.”
The Stoner 63/63A was issued on a trial basis in several configurations to the United States Marine Corps, the Navy SEALs, and U.S. Army Special Forces/MACV-SOG in Southeast Asia.
Although production ended in 1971, the Stoner had loyal followers among America’s special operations units and continued operations with the Navy SEALs and the Marine Corps. The Stoner remained in use with the Mk 23 Model 0 Light Machine Gun configuration until the 1983 invasion of Grenada, and was ultimately replaced by the M249 Squad Automatic Weapon.
In 1971, Cadillac Gage ended development and production of the Stoner 63. Knight’s Armament Company of Titusville, Florida, purchased the remaining Stoner 63 parts and assemblies and produced 100 Stoners. Cadillac Gage produced approximately 4,000 Stoners, most of which were destroyed. Today, a transferable Stoner 63 fetches an enormous price anywhere north of $80,000. It truly was an advanced weapon system that ended before its time.
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