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The Stoner 63 is an American modular weapon system created by Eugene Stoner (one of the designers of the Armalite AR-15) in 1963, although without any country was mass used, the Stoner 63 was used by the U.S. Navy SEALs and by the USMC in limited numbers during the Vietnam War.


Carbine version of Stoner 63

Eugene Stoner, one of designers of M16 rifle, left ArmaLite in about 1961 and joined the Cadillac GageCorp. There he began development of an entirely new weapon system. It was probably the first truly modular system,that consisted of about fifteen subassemblies which could be assembled in any configuration, from an assault rifle and short carbine up to a lightweight or even a general purpose machine gun. First prototypes, chambered for 7.62x51mm NATO ammunition, appeared in 1962, known as Stoner 62. Just a year later Stoner turned out a new system, chamberedfor 5.56x45 M193 US service round, and known as Stoner 63. This system, developed and promoted until the early 1970s, was extensively tested by the US military as the XM22 (Stoner 63A rifle), XM23 (Stoner 63A carbine), and the XM207 (light machine gun with belt feed). The only military application of the Stoner 63 system, however, was the Mk.23 model 0 belt-fed light machine gun configuration, used in limited numbers by US Navy Special Forces and Marine Corps in Vietnam. In general the Stoner system, while having the advantages of modularity and interchangeability of parts and thus great flexibility in tactical use, is too heavy as a rifle, and too expensive and somewhat over-complicated in general. It is also somewhat dirt-sensitive and requires much attention and maintenance. Overall, some 3,500 to 4,000 Stoner 63 weapon kits were produced between 1962 and 1971.

The Stoner 63 is more than just a single firearm; it is a modular kit, which contains about 15 sub-assemblies. Different combinations of those sub-assemblies (barrels, feed units, trigger units, sight units) allow the assembly of various firearms on the single receiver unit. The stamped steel receiver contains an universal bolt group, with a multi-lug rotating bolt and a long stroke gas piston with gas tube. The receiver also has several sets of mounting points for attachment of all other sub-assemblies and the quick-detachable barrel. In rifle and carbine configuration, the receiver is so orientated that the gas system lies above the barrel and the feed unit mounting points are below the receiver. In all machine gun configurations, either belt or magazine fed, the receiver is turned “upside down”, with the gas system being below the barrel, and the feed unit being above the receiver. In rifle/carbine configuration the Stoner 63 system utilizes a hammer-fired trigger unit, integral with the pistol grip and triggerguard. This trigger unit allows for single shots and full auto fire, and the gun is fired from a closed bolt only. In machine gun configuration, the trigger unit has no hammer; instead, its sear interoperates with the cut in the gas piston rod, allowing only full automatic fire, and only from an open bolt. The magazine

U.S Navy SEAL using a Stoner 63 with drum magazine during the Vietnam War

feed unit can accommodate proprietary curved box magazines for 30 rounds, and can be used both in rifle and machine gun configurations. The belt feed unit could be used only in machine gun configurations. Different rear sight units were available for various configurations, with the front sights being mounted on quick detachable barrels. On earlier Stoner 63 system weapons, the charging handle was located on the right side of the bolt carrier; the safety and fire selector were combined in one control, located on the left side of the trigger unit. On the modified Stoner 63A system, the charging handle was attached to the gas piston rod, and projected from the top in rifle / carbine configuration, or from the bottom in MG/LMG configurations; the safety was made as separate lever at the front of the trigger guard, with the fire mode selector still located on the side of the trigger unit, above the pistol grip. The Stoner 63 system featured a variety of easily detachable fixed or folding buttstocks. The latter were available in a side-folding plastic variety, or in an under-folding stamped steel type, similar to the Kalashnikov AKS.


The Stoner 63 was produced in several configurations, with 15 separate assemblies, which had limited parts commonality. These variants included a carbine, an assault rifle, and various light machine guns feeding linked ammunition from the left or right. The gas system was moun

Light Machine Gun variant of the Stoner 63

ted 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. The rifle configuration was field tested by the USMC for a short period during 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 a closed-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 configur

    Stoner 63 with a Bren style of magazine.

    ation fires from an open bolt and is fed from the right-hand side by linked ammunition contained in a 100-round plastic box. 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.
  • 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. The FMG was designed for use with the Cadillac Gage Commando 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.

    Fixed Machine Gun version of the Stoner 63

    This variant was used by some United States Navy SEALs units in Vietnam.
  • Stoner 63 Survival Rifle: The Survival Rifle was designed in 1964 to compete with the Colt Model 608 as an aircrew self-defense weapon. It is mechanically similar to the Rifle configuration, but has several external modifications made to fit into United States Air Force 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.

The most recent descendant of this line is the Stoner LMG produced by Knight's Armament Company, which has significant changes from the older Stoner 63.

Robinson Armament Co. also produces 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.


Caliber: 5.56x45mm
Action: Gas Operated, rotating bolt
Overall Length: 1022mm
Barrel Length: 508mm
Rate of Fire: 750-900 Rounds per Minute
Weight: 30 Rounds

See Also

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