Stoner 63
Cadillac Gage · Machine Gun · Out Of Production · 1963
Also known as: Stoner 63A, Mk 23 Mod 0, XM207, XM22, XM23, Commando, Stoner Weapon System, Cadillac Gage Stoner 63
Overview
The Stoner 63 is a modular 5.56x45mm weapon system designed by Eugene Stoner and produced by Cadillac Gage between 1963 and 1971. Built around a single common receiver group, the system could be reconfigured in under ten minutes into any of roughly fifteen different weapon configurations, including a rifle, carbine, top-feed light machine gun, belt-fed medium machine gun, fixed solenoid-fired machine gun for vehicle mounts, and even a survival configuration. The original Stoner 63 used a long-stroke gas piston action operating from an open bolt in automatic roles and a closed bolt in semi-automatic rifle configuration. The later Stoner 63A refined the design with a short-stroke gas system and various reliability improvements. In its most famous configuration, the Mk 23 Mod 0 Commando light machine gun, the weapon fed from a distinctive 100-round belt housed in a side-mounted drum and became a prized weapon of US Navy SEAL Team ONE and TWO during the Vietnam War, who valued its combination of 5.56mm ammunition weight, sustained firepower, and compact size. Despite extensive US military trials and a reputation for performance, the system's high parts count, mechanical complexity, and demanding maintenance requirements prevented broad adoption, and total production under Cadillac Gage reached only about 4,000 units before manufacturing ceased in 1971.
Specifications
| Weight (empty) | 5300 g (187.0 oz) |
| Overall Length | 1022 mm (40.24") |
| Barrel Length | 508 mm (20.00") |
| Action Type | Gas Operated Long Stroke |
| Firing Mechanism | Open Bolt |
| Trigger Type | Select Fire |
| Magazine Capacity | 100 rounds |
| Magazine Type | Belt |
| Muzzle Velocity | 990 m/s (3248 fps) |
| Muzzle Energy | 1745 J (1287 ft·lbf) |
| Effective Range | 800 m (875 yd) |
| Maximum Range | 2653 m (2901 yd) |
| Rate of Fire | 700 rpm |
| Barrel Rifling | Right Hand |
| Rifling Twist | 305 mm (12.01") |
| Number of Grooves | 6 |
| Frame Material | Steel |
| Barrel Material | Steel |
| Stock Material | Polymer |
| Finish | Parkerized |
Calibers
- 5.56x45mm NATO · primary · 5.56x45mm NATO — also known as 5.56mm NATO, 5.56x45mm, M193, .223 Remington
Features
- Firing modes: Semi Automatic, Full Automatic
- Feed systems: Belt, Detachable Box, 100 Round Assault Drum
- Safety mechanisms: Manual Safety, Open Bolt System
- Features: Modular Design, Quick Change Barrel, Folding Bipod, 100 Round Drum Belt, Convertible Feed System, Carry Handle, Interchangeable Configuration, Top Mounted Belt Feed, Bottom Mounted Magazine Feed
Variants
- Stoner 63 Rifle — Configuration
- Stoner 63 Carbine — Configuration
- Stoner 63 Light Machine Gun — Configuration
- Stoner 63 Medium Machine Gun — Configuration
- Stoner 63 Fixed Machine Gun — Configuration
- Stoner 63 Survival Rifle — Configuration
- Stoner 63A — Improved
- Stoner 63A1 — Improved
- Mk 23 Mod 0 Commando — Military Designation
- XM207 — Us Army Trials
- XM22 Rifle — Us Army Trials
- XM23 Carbine — Us Army Trials
Service history
Operators
- United States Navy SEALs · adopted 1967 · as Mk 23 Mod 0
- United States Marine Corps · adopted 1966 · as Stoner 63 (trials)
- United States Army · adopted 1965 · as XM207 (trials)
- Nicaraguan National Guard · as Stoner 63A
Conflicts
- Vietnam War (1967-1971)
- Nicaraguan Revolution (1978-1979)
Production
Estimated total produced: 4,000 · Production years: 1963-1971
Approximately 4,000 units produced by Cadillac Gage under license from Stoner's design work at Cadillac Gage's Warren, Michigan facility. Small additional quantities assembled from spares by NWM De Kruithoorn in the Netherlands for limited export.
Origin
Country of origin: United States
Designer: Eugene Stoner
Discontinued: 1971
Notes
The Stoner 63 pioneered the modular weapon concept decades before systems like the FN SCAR and the HK416. The core assembly consisted of a receiver, barrel, trigger group, and feed mechanism that could be reassembled in multiple orientations: the same receiver could be inverted so the magazine fed from below (rifle/carbine) or from the top with a belt feed mechanism added (LMG/MMG). The Mk 23 Mod 0 Commando variant used by Navy SEALs was chambered for 5.56x45mm M193 and fed a linked belt from a 100-round drum that clipped to the left side of the receiver. SEAL operators praised the weapon's firepower-to-weight ratio in jungle patrols along Vietnamese waterways, though armorers noted the complex gas system and exposed feed pawls were vulnerable to mud, sand, and silt. The Stoner 63A was submitted to the US Army for Small Arms Weapons System (SAWS) trials but lost to the M60 and eventual M249 programs. Training and logistical costs associated with supporting a single-unit weapon system outside the Navy special warfare community were cited as a major factor in its retirement from SEAL service in 1983.
Background
Eugene Stoner designed the Stoner 63 while at Cadillac Gage after leaving ArmaLite, aiming to build a single weapon that could replace an entire family of small arms with ten minutes and a handful of pins. Navy SEALs loved the Mk 23 Commando so much that operators would hand-wrap its 100-round belt drums in cloth tape to waterproof them before inserting the team into the Mekong Delta at night. The Stoner's modular concept was so far ahead of its time that it would take nearly forty years before comparable systems like the FN SCAR and HK XM8 attempted the same trick, and even then without the ability to swap between rifle and belt-fed machine gun on the same receiver.