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The Stoner 63 is a 5.56×45mm NATO
modular weapon system A modular weapon system (MWS) is any weapon equipment which has removable core components (or " modules") that can be reconfigured/interchanged to give the weapon different capabilities to adapt to various applications. Modularity can provide se ...
. Using a variety of modular components, it can be configured as an assault rifle,
carbine A carbine ( or ) is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges. The smaller size and lighte ...
, top-fed
light machine gun A light machine gun (LMG) is a light-weight machine gun designed to be operated by a single infantryman, with or without an assistant, as an infantry support weapon. LMGs firing cartridges of the same caliber as the other riflemen of the s ...
,
belt-fed upright=1.35, An M60 machine gun belt loaded with 7.62×51mm NATO cartridges, aboard a U.S. Navy">7.62×51mm_NATO.html" ;"title="M60 machine gun belt loaded with 7.62×51mm NATO">M60 machine gun belt loaded with 7.62×51mm NATO cartridges, aboar ...
squad automatic weapon A squad automatic weapon (SAW), also known as a section automatic weapon or light support weapon (LSW), is a man-portable automatic firearm attached to infantry squads or sections as a source of rapid direct firepower. Weapons fulfilling th ...
, or as a vehicle mounted weapon. Also known as the M63, XM22'', ''XM23, XM207 or the Mk 23 Mod 0 machine gun, it was designed by
Eugene Stoner Eugene Morrison Stoner (November 22, 1922 – April 24, 1997) was an American firearms designer who is most associated with the development of the ArmaLite AR-15 rifle that was redesigned and modified by Colt's Patent Firearm Company (now known ...
in the early 1960s. Cadillac Gage was the primary manufacturer of the Stoner 63 during its history. The Stoner 63 saw very limited combat use by United States forces during the
Vietnam War The Vietnam War (also known by other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vietna ...
. A few were also sold to law enforcement agencies.


History


Development

Soon after leaving
ArmaLite ArmaLite, or Armalite, is an American small arms engineering company, formed in the early 1950s, in Hollywood, California. Many of its products, as conceived by chief designer Eugene Stoner, relied on unique foam-filled fiberglass butt/stock fu ...
,
Eugene Stoner Eugene Morrison Stoner (November 22, 1922 – April 24, 1997) was an American firearms designer who is most associated with the development of the ArmaLite AR-15 rifle that was redesigned and modified by Colt's Patent Firearm Company (now known ...
, one of the United States' most prolific modern military small arms designers, responsible for the design of the
ArmaLite AR-15 The ArmaLite AR-15 is a select-fire, gas-operated, air-cooled, magazine-fed rifle manufactured in the United States between 1959 and 1964. Designed by American gun manufacturer ArmaLite in 1956, it was based on its AR-10 rifle. The ArmaLite ...
/ M16 assault rifles,
ArmaLite AR-10 The ArmaLite AR-10 is a 7.62×51mm NATO battle rifle designed by Eugene Stoner in the late 1950s and manufactured by ArmaLite (then a division of the Fairchild Aircraft Corporation). When first introduced in 1956, the AR-10 used an innovative co ...
battle rifle A battle rifle is a service rifle chambered to fire a fully powered cartridge. The term "battle rifle" is a retronym created largely out of a need to better differentiate the intermediate-powered assault rifles (e.g. the StG-44, AK-47, M16, ...
and
Armalite AR-7 The ArmaLite AR-7 Explorer is a semi-automatic firearm in .22 Long Rifle caliber, developed in 1959 from the AR-5 that was adopted by the U.S. Air Force as a pilot and aircrew survival weapon. The AR-7 was adopted and modified by the Israeli Ai ...
survival rifle, among others,Kokalis, Peter: ''Weapons Tests And Evaluations: The Best Of Soldier Of Fortune'', page 160. Paladin Press, 2001. devised a concept for a modular weapon that would be built around a common receiver and certain interchangeable components and could be transformed into a rifle,
carbine A carbine ( or ) is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges. The smaller size and lighte ...
or various
machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle ri ...
configurations by simply fitting the appropriate parts to the basic assembly.Kokalis, 161 Stoner managed to solicit the help of Howard Carson, in charge of Cadillac Gage's West Coast plant in Costa Mesa,
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the mo ...
(where Armalite was also located), in convincing the company's president, Russell Baker, of the feasibility and commercial potential of his new weapons system. Russell obliged and Cadillac Gage (a subsidiary of the Ex-Cell-O Corporation) established a small arms development branch in Costa Mesa. Stoner then recruited his two principal aides at Armalite: Robert Fremont and James L. Sullivan (who would later design the Ultimax 100
light machine gun A light machine gun (LMG) is a light-weight machine gun designed to be operated by a single infantryman, with or without an assistant, as an infantry support weapon. LMGs firing cartridges of the same caliber as the other riflemen of the s ...
for the Chartered Industries of Singapore). The first working prototype was chambered in
7.62×51mm NATO The 7.62×51mm NATO (official NATO nomenclature 7.62 NATO) is a rimless, bottlenecked rifle cartridge. It is a standard for small arms among NATO countries. First developed in the 1950s, the cartridge had first been introduced in U.S. service ...
and completed in 1962. It was designated the Stoner M69W (for no other reason than when turned upside down it reads the same, symbolizing Stoner's vision of a fully invertible receiver). The follow-up design, called the Stoner 62, also chambered in 7.62×51mm, was intended for mass production. However, the design team decided to focus on the 5.56×45mm small caliber high-velocity cartridge, as it appeared the new round was gaining mainstream military approval. Eugene Stoner had previously worked with the cartridge when he designed the AR-15. The weapon system using the smaller cartridge was known as the Stoner 63. The first models were produced in February 1963. The Costa Mesa facility produced 234 Stoner 63s, when production was then moved in September 1964 to the Cadillac Gage plant in
Warren A warren is a network of wild rodent or lagomorph, typically rabbit burrows. Domestic warrens are artificial, enclosed establishment of animal husbandry dedicated to the raising of rabbits for meat and fur. The term evolved from the medieval A ...
,
Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...
. With the change in manufacturing plants, polycarbonate plastic was used for the stocks and grips instead of wood. The weapon is covered under .


Trials

On March 4, 1963, the Department of Defense's
Advanced Research Projects Agency The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Adv ...
made the first purchase of the Stoner 63, ordering 25 units in various configurations. In August and September 1963, the Stoner 63 was sent to the Marines Corps Landing Force Development Center at Quantico for evaluation, where it made a positive impression with its light weight and high ammunition capacity; the Marines favored the rifle and light machine gun configurations. Trials were performed by the Army Materiel Command (responsible for logistical support for the Marine Corps) at their own test facilities. Many bugs affected the outcome of the Army trials of the gun: the ammunition requirements proposed were unrealistic and the weapon was expected to perform with an extremely wide range of port pressures, leaving very little power reserve with some ammunition types. For instance, the tracer ammunition used in the Stoner 63 was of such low pressure that it even failed to function reliably in the M16. These factors severely affected the weapon's reliability. After several months of testing, the Stoner 63 system was ultimately deemed to be unacceptable for service use. The Army submitted recommendations for improvements to the design—these included a
stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's r ...
gas cylinder, a two-position fire selector with separate safety, ejection port dust covers and modifications to the belt feed mechanism. The upgrades resulted in the improved Stoner 63A, which began production in 1966.Kokalis, 163 Only about 2,000 examples of the initial version were manufactured before the transition to the model 63A. XM207 upgrades From 1969 to 1971 Cadillac Gage Co initiated a program to upgrade the Stoner 63 light machine gun due to Marine Corps interest. They were given one last chance to make design improvements and have a final test by the Army Materiel Command. Several changes were made to the weapon, soon to be designated "XM207 Light Machine Gun". Misfires, high cyclic rates, jams and link separations were among the issues to be resolved. The 63A used a stack of Belleville spring washers to absorb some of the shock and bounce when the firing pin struck the primer. By changing the configuration of the washers, a higher spring rate was achieved, and this was the solution for the bulk of the misfires. The weapon, when cold, would fire at about 650 rounds per minute (rpm). When it was very hot, after several hundred rounds had been fired, the cyclic rate climbed as high as 1,100 rpm. The mechanical functions of the weapon just would not work properly at these high rates. There were several problems that occurred at high RPM, including link separation. A "rate regulator" similar to that used in
M60 machine gun The M60, officially the Machine Gun, Caliber 7.62 mm, M60, is a family of American general-purpose machine guns firing 7.62×51mm NATO cartridges from a disintegrating belt of M13 links. There are several types of ammunition approved fo ...
was installed in the
buttstock A gunstock or often simply stock, the back portion of which is also known as a shoulder stock, a buttstock or simply a butt, is a part of a long gun that provides structural support, to which the barrel, action, and firing mechanism are attache ...
. It was basically a shock absorber (designed by Cadillac Gage Co) that eliminated the recoil bounce off the back plate. This allowed the main drive spring to control the forward velocity of the carrier. With the "rate regulator" installed the cyclic rate of the weapon was limited to about 800 rpm. This resolved the mechanical malfunctions that occurred above 1,000 rpm. In combination with the "rate regulator" changes were made to the belt feed system for better reliability. Another issue was low gas pressure when firing tracer rounds, causing failures to cycle. The addition of an expandable steel sealing ring in the gas chamber kept the external gas leaks to a minimum, retaining enough gas pressure to cycle the action reliably. The next issue was the
polycarbonate Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily wor ...
buttstock being unable to withstand the 5,000+ pound recoil force of firing anti-tank grenades. With the weapon's tight weight restriction, using a heavier metal buttstock was not an option. Several ribbed designs were evaluated, but none were successful. The solution was to pressure-fill the hollow buttstock with a lightweight urethane foam, imparting structural rigidity and high impact strength. This solved the problem without going over the weight limit, and made the buttstock extremely durable. Several weapons with these improvements were produced by Cadillac Gage for testing by the Army Materiel Command. This would be the last chance for the weapon, now designated XM207. With its latest design changes, the weapon passed all tests. But soon afterwards, president Nixon announced that the United States would be withdrawing from Vietnam, eliminating the urgency to adopt a new infantry weapon. The XM207 project was cancelled.


Deployment

Even very early on in its development stage, a small number of weapons were hurriedly pressed into service with the U.S. Navy SEALs deployed to
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland ...
. During 1967, the Stoner 63A system was field tested by Company L (Lima Company), 3rd Battalion, 1st Marine Regiment,
1st Marine Division The 1st Marine Division (1st MARDIV) is a Marine division of the United States Marine Corps headquartered at Marine Corps Base Camp Pendleton, California. It is the ground combat element of the I Marine Expeditionary Force (I MEF). It is th ...
. Riflemen were issued the weapon in the Rifle configuration (in both 63 and 63A variants, designated XM22 and XM22E1 respectively), while officers and certain other personnel received the Carbine (XM23). The Automatic Rifle configuration was deployed on a limited basis in the squad automatic role, while Lima's weapons platoon received both the LMG and MMG configurations. In 1967, Dutch firm NWM (Nederlandsche Wapen-en Munitiefabriek) De Kruithoorn N.V. of
's-Hertogenbosch s-Hertogenbosch (), colloquially known as Den Bosch (), is a city and municipality in the Netherlands with a population of 157,486. It is the capital of the province of North Brabant and its fourth largest by population. The city is south of th ...
acquired licensing rights to manufacture and sell the weapon worldwide with the exception of the United States, Canada and Mexico. NWM assembled several prototypes but the company failed to secure any export customers and the weapon was withdrawn. The Stoner 63 was also considered for the Swiss armed forces as the W+F Stgw 71 In 1970, the U.S. Army designated the light machine gun configuration XM207 and issued it to select
Army Special Forces The United States Army Special Forces (SF), colloquially known as the "Green Berets" due to their distinctive service headgear, are a special operations force of the United States Army. The Green Berets are geared towards nine doctrinal ...
units for evaluation. However, due to its complexity and high maintenance requirements (especially when compared to the new M16), the design was rejected, and the project was dropped in 1971. That same year, Cadillac Gage ceased all production of the Stoner 63. Around 4,000 63 and 63A units were built in total. The Navy SEALs continued to use the Stoner 63 and had officially adopted the Commando version as the Mark 23 Mod 0 machine gun. By the late 1980s the Stoner 63 was completely phased out in favor of the new M249 SAW, and most of the remaining guns were destroyed.


Design details


Operating mechanism

The Stoner 63 series of weapons are piston driven, air-cooled, belt or
magazine A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combina ...
-fed and in rifle and carbine configuration, fire from a
closed bolt A semi or full-automatic firearm which is said to fire from a closed bolt is one where, when ready to fire, a round is in the chamber and the bolt and working parts are forward. When the trigger is pulled, the firing pin or striker fires the ...
to ensure maximum accuracy, or in machine gun mode, fire from the
open bolt A firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a cartridge from ...
position to prevent cook-offs and enhance cooling. The weapon has a rotary bolt locking mechanism with 7 radially symmetrical locking lugs that engage a series of recesses in the
barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...
extension, and is actuated by a conventional long-stroke piston. The radial arrangement of locking lugs distributes the firing load evenly around the bolt head and barrel socket, reducing stress and increasing the longevity of these critical components. Attached to the piston extension is the bolt carrier which is equipped with a curved cam track that guides the bolt's cam pin (retained by the
firing pin A firing pin or striker is a part of the firing mechanism of a firearm that impacts the primer in the base of a cartridge and causes it to fire. In firearms terminology, a striker is a particular type of firing pin where a compressed spri ...
) and rotates the bolt 22.5° during the movement of the piston to either lock or unlock the bolt from behind the abutments in the barrel socket. Incorporated into the bolt carrier/piston group is an anti-bounce device, consisting of a
carbide In chemistry, a carbide usually describes a compound composed of carbon and a metal. In metallurgy, carbiding or carburizing is the process for producing carbide coatings on a metal piece. Interstitial / Metallic carbides The carbides of the ...
rod that rides within the piston extension's hollow interior and moves back and forth during the recoil and counter-recoil cycles, reducing bolt bounce and preventing the possibility of firing out of battery during closed bolt firing (in the Rifle/Carbine models). When fired, propellant gases from the ignited cartridge following the projectile down the bore are vented through a gas port into a gas cylinder where they drive the piston and bolt carrier rearward. There is about of uninterrupted free travel calculated to permit the gas build-up in the bore to drop to a safe level before the carrier's cam slot rotates the bolt counter-clockwise to unlock. The locking lugs have no pitch therefore no
primary extraction In breechloading firearms, primary extraction is the initial phase (the first few millimeters) of the extraction of a spent casing from the firearm chamber. After the primary extraction comes the secondary extraction where the bolt is moved f ...
occurs during the unlocking sequence. A deeply seated spring-loaded claw extractor in the bolt head extracts the spent cartridge casing from the chamber and a spring-powered ejector fixed to the front feed mechanism
trigger Trigger may refer to: Notable animals and people ;Mononym * Trigger (horse), owned by cowboy star Roy Rogers ;Nickname * Trigger Alpert (1916–2013), American jazz bassist * "Trigger Mike" Coppola (1900–1966), American gangster ;Surname * Bru ...
housing ejects the casing. The bolt carrier continues to the rear and compresses the captive recoil spring on its guide rod. The Stoner 63 has a unique buffering system contained within the bolt carrier. In front of the carrier cap are a
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resist ...
shim and a set of 27 saucer-shaped Belleville washers oriented in opposing sets of three, which absorb energy from the piston stroke by deforming into a flat plate when the bolt carrier strikes the receiver's end cap. When the plates return to their original shape they release a pulse of
strain energy In physics, the elastic potential energy gained by a wire during elongation with a tensile (stretching) force is called strain energy. For linearly elastic materials, strain energy is: : U = \frac 1 2 V \sigma \epsilon = \frac 1 2 V E \epsil ...
which propels the reciprocating parts forward in counter-recoil with a speed only slightly below that of the original recoil velocity. The plates will function without failure for between 40,000 and 50,000 rounds (depending upon the type of ammunition used and cyclic rates employed). This feature was designed to extend the weapon's service life.


Feeding

In the belt-fed configuration, belt movement is produced by a roller riding in the channeled feed arm and is actuated by the reciprocating movement of the bolt. The spring-loaded feed arm is protected by a hinged top cover and is pivoted at its rear end. As the bolt travels back, the front end of the feed arm moves across the feed tray and operates a lever attached to a single set of spring-loaded pawls. These pawls move a cartridge and link over the feed tray's stop pawl from where they are positioned onto the slotted feed path and held firmly in place by a spring-powered steel plate in the top cover. The cartridge is then pushed out of its link and the empty link is discarded through the link ejection port which is held closed by a spring-loaded dust cover. The Stoner 63/63A is chambered for the now-standard 5.56×45mm intermediate rifle cartridge. When in the belt-fed role, the weapon would feed from a disintegrating metallic linked belt marked "S-63 BRW" which is a scaled-down version of the U.S.
M13 link The M13 link, formally Link, Cartridge, Metallic Belt, 7.62mm, M13, is the U.S. military designation for a metallic disintegrating link specifically designed for ammunition belt-fed firearms and 7.62×51mm NATO rounds. It was introduced in th ...
developed for the M60 GPMG. The Stoner 63/63A will not work reliably with the later M27 link developed for the M249 SAW. The belt is normally contained in a 150-round plastic ribbed container that has a tab allowing it to be clipped on to the side of the left-hand feed tray. Early ammunition boxes were olive drab in color and manufactured at Costa Mesa, this later changed to a black-colored plastic container made in Warren, Michigan. Stoner 63A boxes were also black but had a reduced capacity of 100 rounds as the larger container would unbalance the rifle. These can either be attached to the left-hand feed tray or held in a bottom box carrier when using the right-hand feed mechanism. Several drum-type belt carriers were designed for the left-hand feed system, with a 150-round drum container being the most popular and used frequently by SEALS in Vietnam. A 250-round drum carrier was also developed by NAWS China Lake, but this proved too heavy and cumbersome. SEALS would also resort to converting RPD belt carriers for use with their Stoners. The detachable magazines used in the Rifle, Carbine and Automatic Rifle models are fabricated from steel and weigh unloaded. In an effort to reduce weight,
aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
magazines were later developed cutting the weight down to . Standard magazines have a 30-round cartridge capacity but a 20-round magazine was also offered.


Barrel

Barrel interchangeability is one of the main features that provides the Stoner 63 rifle its outstanding versatility. There are 5 barrel options available for the system: the Rifle, Carbine, Automatic Rifle (AR) and two types of machine gun barrels, a standard heavy barrel and a short Commando tube. The standard machine gun and AR barrels are in length (not including the
flash suppressor A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a muzzle device attached to the muzzle of a rifle that reduces its visible signature while firing by cooling or dispersing the burning gases that ...
). The Commando barrel has a length of and is fluted to reduce weight and enhance the barrel's cooling characteristics. This version was sometimes used by the Navy SEALS but was never fully reliable as the gas port is near the muzzle and as soon as the bullet leaves the barrel, gas pressures drop drastically leaving the operating system little to no power reserve. The gas port was drilled larger in an attempt to alleviate this problem; however this had the effect of merely accelerating the piston's initial displacement. The issue was never truly resolved. The Rifle, Carbine and AR barrels have no gas valves as they are exclusively used in magazine-fed configurations and do not require the energy surplus levels of belt-fed mechanisms. The standard machine gun barrel has a manually adjustable gas regulator that can be operated by inserting the nose of a cartridge into a hole over the regulator's lock detent, pushing down on the detent and rotating to the desired position. The gas regulator has three settings: a "slow" cyclic rate of about 700 rounds/min, produced when the narrowest indicator notch is set over the detent; a middle position with an intermediate rate of 830 rounds/min and a third "fouled" position that delivers the largest quantity of propellant gas to the system, resulting in a rate of fire of 865 rounds/min (the use of this setting should be limited as it induces excessive wear on the operating mechanism). All Stoner 63/63A barrels are gas nitrided and have a quick-detach capability and can be removed in a matter of seconds in field conditions by simply pushing down a latch located on top of the weapon in front of the feed cover and pulling the barrel forward (with the bolt retracted). The chamber portion of the barrel rests on a U-shaped barrel bracket attached to the gas cylinder. The barrel is firmly locked in position by means of a spring-loaded latch (with two nested coil springs) which drives a steel pin into a hole in the barrel socket. All barrels have a gas block to which a
bayonet lug A bayonet lug is a standard feature on most military muskets, rifles, and shotguns, and on some civilian longarms. It is intended for attaching a bayonet, which is typically a long spike or thrusting knife. The bayonet lug is the metal mount th ...
and front sight assembly are mounted. The barrels are equipped with a bird cage type flash suppressor with six oval ports. The AR and standard machine gun barrels also have a carrying handle that can be snapped into one of three positions or removed altogether. The black-painted wooden handles are attached to a steel rod via roll pin. With a few exceptions, all the barrels used in the Stoner 63/63A have a six-groove right-hand rifling with a twist rate of 1:12-inch (305 mm), designed to stabilize the lightweight 55-
grain A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legume ...
M193 projectile, which was standard at the time. At the Army's request, Cadillac Gage submitted for testing rifles, carbines, and light machine guns, with 1:9-inch (230 mm) twist barrels, respectively designated XM22E2, XM23E2, and XM207E2. The different twist was to test the 68-grain XM287 and XM288 bullets. After NWM obtained a license to produce the Stoner 63A, some barrels were manufactured with a 1:8-inch (200 mm) in rifling pitch to be used with heavier experimental bullets. None of these were ever produced in significant numbers.


Fire control

The Stoner 63/63A LMG is an automatic weapon that fires from the open bolt and the trigger mechanism permits only fully automatic firing though burst size can be controlled by the shooter. The entire trigger unit has four trigger pins that give the unit its modularity. The front pin holds a flapper-type magazine catch/release (used in the Rifle/Carbine variants and the left-hand feed LMG with a 150-round drum-type belt container), a full dust cover (used with the top-feeding Automatic Rifle or vertically mounted ammo box on any belt-fed system) or a half size dust cover (used with the right-hand-feed bottom box carrier). The next two pins retain the timer and hammer, both of which are absent in the open bolt configurations. The final pin acts as the trigger's axis shaft; the spring-loaded sear pivots on the selector lever's axis pin. The selector is disconnected when firing from the open bolt and a sliding manual safety installed near the trigger guard disables the trigger when pushed to the rear. The rear portion of the trigger housing serves as a receiver end cap and is used to attach the shoulder
stock In finance, stock (also capital stock) consists of all the Share (finance), shares by which ownership of a corporation or company is divided.Longman Business English Dictionary: "stock - ''especially AmE'' one of the shares into which owners ...
. The black
polycarbonate Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily wor ...
pistol grip On a firearm or other tools, a pistol grip is a distinctly protruded handle underneath the main mechanism, to be held by the user's hand at a more vertical (and thus more ergonomic) angle, similar to the how one would hold a conventional pi ...
is also attached to the trigger housing. The checkered grip is flared at the bottom to prevent the shooter's hand from sliding off and has an internal storage compartment sealed by a hinged cover with a spring-loaded hatch.


Features

The hooked, non-reciprocating steel charging handle is typically mounted on the right side of the receiver. It has 24
lightening holes Lightening holes are holes in structural components of machines and buildings used by a variety of engineering disciplines to make structures lighter. The edges of the hole may be flanged to increase the rigidity and strength of the component. ...
and engages a projection on the piston to draw the piston and bolt group to the rear (cocked) position. The handle should then be pushed back forward allowing a flat-spring latch riveted to the front end to capture a slotted plate welded to the front of the receiver. With the right-hand feed mechanism with underslung box carrier installed the handle is awkward to operate, so a special slotted forearm with a bottom cocking handle was developed. The nucleus of the Stoner 63 system is the receiver which is a rectangular
sheet metal Sheet metal is metal formed into thin, flat pieces, usually by an industrial process. Sheet metal is one of the fundamental forms used in metalworking, and it can be cut and bent into a variety of shapes. Thicknesses can vary significantly; e ...
pressing. The gas cylinder, support structures, brackets, lugs and other devices are welded in place. The front portion carries the piston and barrel and is perforated to reduce weight and improve air circulation around the barrel and gas cylinder. The rear segment holds the piston extension and bolt group. The ejection port is on the right side when the receiver is inverted and the weapon is configured as a rifle or carbine and on the left side when in the various machine gun roles. The various components are phosphate finished and then coated with a black baked enamel finish called Endurion. Early examples of the Stoner 63 were delivered with all wood furniture, however these were soon replaced with black polycarbonate parts with the exception of the handguard, which remained wood, but was painted black. The Stoner 63
bipod A bipod is a V-shaped portable attachment that helps support and steady a device, usually a weapon such as a long gun or a mortar. The term comes from the Latin prefix ''bi-'' and Greek root ''pod'', meaning "two" and "foot" respectively. Bi ...
is a non-locking type that attaches to the gas tube; it does not pivot and has a limited height adjustment feature. The Stoner 63A bipod is extensively perforated with lightening holes and can be locked in either the stowed or deployed positions. It too does not pivot but is compatible with the earlier Stoner 63, whereas the Stoner 63 bipod will not work with the later 63A pattern guns as the gas tube is of a larger diameter.


Sights

The sight arrangement on the Stoner 63/63A differs amongst the various configurations. On the belt-fed LMGs, the rear sights are mounted on the top cover. These consist of a folding leaf aperture elevation scale graduated in 100 m increments from 200 to 1,000 m. The rear sight can also be corrected for windage in ¼- mil increments. When the primary sight is folded down, a battle sight aperture with a diameter of is exposed. The Rifle and Carbine versions have simple flip-type apertures with settings for 0–300 and 300–500 m contained between large perforated protective ears. The sights are adjustable in both windage and elevation in 1
MOA Moa are extinct giant flightless birds native to New Zealand. The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as Kale moa and Moa Samoa. Moa or MOA may also refer ...
increments. All variants share the same front sight assembly—a semi-shrouded round threaded post adjustable for windage and elevation zero (similar to the M16 front sight).


Accessories

The Stoner 63/63A is supplied with several accessories, including: a blank-firing attachment (BFA), winter trigger guard,
asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere ...
-lined spare barrel bag, cleaning kit, 40 mm
grenade launcher A grenade launcher is a weapon that fires a specially-designed large-caliber projectile, often with an explosive, smoke or gas warhead. Today, the term generally refers to a class of dedicated firearms firing unitary grenade cartridges. The most ...
, several types of slings and a wide range of belt box and magazine pouches. The Stoner 63/63A used three different types of
bayonet A bayonet (from French ) is a knife, dagger, sword, or spike-shaped weapon designed to fit on the end of the muzzle of a rifle, musket or similar firearm, allowing it to be used as a spear-like weapon.Brayley, Martin, ''Bayonets: An Illustra ...
s: the standard U.S. M7, the KCB 70, developed specifically for this rifle by the West German company Eickhorn-Solingen together with NWM and a rare bayonet made by the Swiss industrial conglomerate SIG. The KCB 70 features a long Bowie blade with a clip-point and an integrated wire-cutter, it was inspired by
Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...
bayonets for the AKM. A highly successful multi-purpose tool, it evolved into the KCB 77, a modular design that was adapted to many different assault rifles.


Variants

The Stoner 63 was produced in several configurations, with 15 separate assemblies, which had limited parts commonality. These variants included a
carbine A carbine ( or ) is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges. The smaller size and lighte ...
, an assault rifle, and various
light machine gun A light machine gun (LMG) is a light-weight machine gun designed to be operated by a single infantryman, with or without an assistant, as an infantry support weapon. LMGs firing cartridges of the same caliber as the other riflemen of the s ...
s feeding linked ammunition from the left or right. The gas system was mounted in different positions depending on the weapon's configuration. Due to the multi-role nature of the design the carbine and rifle versions were heavier than comparable weapons of the same type. * Stoner 63/63A Rifle: A standard assault rifle fed from below by a 30-round box magazine. Spent cases are ejected to the right. The cocking handle and gas system are mounted above the barrel. Unlike the belt-fed configurations, the Rifle fires from
closed bolt A semi or full-automatic firearm which is said to fire from a closed bolt is one where, when ready to fire, a round is in the chamber and the bolt and working parts are forward. When the trigger is pulled, the firing pin or striker fires the ...
. The rifle configuration was field tested by the USMC for a short period during April to June 1964 by a recruit company at MCRD Parris Island, SC and elsewhere in 1967. It was eventually fitted with a lightweight bipod that folded beneath the handguard. * Stoner 63/63A Carbine: The Carbine is similar to the Rifle configuration, but with a shorter barrel and a folding shoulder stock. The carbine configuration was field tested by the USMC for a short period during 1967. * Stoner 63/63A Automatic Rifle: The Automatic Rifle is an open-bolt rifle fed from a top-mounted, 30-round magazine. The front and rear sights are offset to the left to compensate for the magazine's position. The AR does not have a semi-automatic mode. The automatic rifle configuration was field tested by the USMC for a short period during 1967. * Stoner 63/63A Light Machine Gun: The LMG configuration fires from an open bolt and is fed from the right-hand side by linked ammunition contained in a 75, 100, 150-round drum magazine. The receiver is identical to the Rifle variants, but is inverted, so that spent cases and links are ejected to the left. The LMG has a quick-change barrel and the gas cylinder is positioned below the barrel since the receiver is inverted. The LMG configuration was adopted for military use by Navy SEAL units operating in Southeast Asia. * Stoner 63/63A Medium Machine Gun: Identical to the LMG configuration. The difference is that the MMG comes with a separate adapter than can be used to attach the weapon to an M2 or
M122 tripod The M2 Tripod is a U.S. machine gun tripod originally used with the Browning M1919 infantry machine gun. Since then, it has seen several redesigns, but remained largely the same. In this fashion, the M2 tripod has seen combat service in every con ...
. * Stoner 63/63A Fixed Machine Gun: Internally identical to the LMG configuration. Externally, the front sights, rear sights, foregrip and pistol grip are all removed. The trigger is activated remotely by a 24V
solenoid upright=1.20, An illustration of a solenoid upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whose ...
. The FMG was designed for use with the
Cadillac Gage Commando The Cadillac Gage Commando, frequently denoted as the M706 in U.S. military service, is an American armored car designed to be amphibious. It was engineered by Cadillac Gage specifically for the United States Military Police Corps during the ...
APC, but was never officially adopted. * Stoner 63/63A Commando: The Commando is a derivative of the LMG configuration. It is fed from the right by a 100-round drum magazine clipped below the receiver. The cocking handle is mounted underneath the foregrip for easier access. To save weight, the Commando eschews the quick-change barrel found on the other belt-fed configurations. This variant was used by some United States Navy SEAL units in Vietnam. * Stoner 63 Survival Rifle: The Survival Rifle was designed in 1964 to compete with the Colt Model 608 as an
aircrew Aircrew, also called flight crew, are personnel who operate an aircraft while in flight. The composition of a flight's crew depends on the type of aircraft, plus the flight's duration and purpose. Commercial aviation Flight deck positions ...
self-defense weapon. It is mechanically similar to the Rifle configuration, but has several external modifications made to fit into
United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sign ...
size constraints. These include a cut-down pistol grip, an absent handguard, shortened barrel and receiver, and a top-mounted cocking handle. The Survival Rifle does not incorporate the 63A upgrades. Only one prototype was ever produced—it survives to this day. * Stoner 66 Civilian Rifle: A short-lived semi-automatic version for the civilian market. Never actually allowed to be sold. The most recent descendant of this line is the
Stoner LMG The Knight's Armament Company Light Assault Machine Gun (LAMG) is a light machine gun system developed by Eugene Stoner and manufactured by Knight's Armament Company (KAC). It was previously known as the Knight's Armament Company LMG. It is the ...
produced by
Knight's Armament Company Knight's Armament Company (KAC) is an American firearms and firearms parts manufacturer, best known for producing the Rail Interface System (RIS) and the Rail Adapter System (RAS) grips for firearms use. They currently produce a variety of firea ...
, which has significant changes from the older Stoner 63, being based on Stoner's later model 86. Robinson Armament Co. also produced the semi-automatic M96 Expeditionary Weapon System which, though technically different, was based on the Stoner 63 design, and thus has some of its features and configurations.


Dutch variants

Although none were manufactured in the Netherlands, around 315 were modified and improved by NWM De Kruithoorn N.V. in various configurations for possible use in the Dutch Armed Forces as the Stoner 63A1 consisting of 6 variantsThe World's Assault Rifles By Gary Paul Johnston, Thomas B. Nelson, Chapter 67: United States, The Stoner Weapons System One of the main modifications was an MP40 (later AK47) type underfolding and later side folding stock, a carbine, an assault rifle, heavy barrel assault rifle, belt fed machine gun, commando machine gun and fixed machine gun. The Stoner 63A1 was tested by the US Army and USMC as the XM22 assault rifle, XM23 carbine and XM207 machine gun. Various improvements was the Dutch pattern side folding stock, quick release bipod that folded under the handguard, an improved removable magazine floor plate, a quick release scope mount.


Designations

The rifle, carbine, commando, and LMG variants were all given designations by the US Military. They are as follows:


See also

* Colt Machine Gun * Ares Shrike 5.56 *
List of assault rifles An assault rifle is a rifle that uses an intermediate cartridge, a detachable magazine, and can switch between semi-automatic/ fully automatic fire. Assault rifles are currently the standard service rifles in most modern armies. Some rifles list ...
* List of carbines * List of machine guns


References


Bibliography

* *


External links

{{commons category, Stoner 63 LMG
Modern Firearms





Forgotten Weapons page

Stoner 63, 63A, & Mk23: History and Mechanics
5.56×45mm NATO machine guns 5.56×45mm NATO assault rifles Squad automatic weapons Rifles of the United States Modular firearms Military equipment introduced in the 1960s