Stoner 63A
Cadillac Gage · Machine Gun · Discontinued · 1966
Also known as: Stoner 63A1, Mk 23 Mod 0, XM207
Overview
The Stoner 63A is the improved 1966 production version of Eugene Stoner's revolutionary 5.56x45mm modular weapon system, built by Cadillac Gage. From a single Basic Component Group of subassemblies it could be reconfigured into six distinct weapons: rifle, carbine, fixed/solenoid-fired machine gun, magazine-fed LMG, belt-fed LMG, and a tripod-mounted medium machine gun. The 63A introduced stainless-steel gas tubes, a trigger-guard safety lever, and revised charging handles over the original 63. Its only operational military use was as the belt-fed Mk 23 Mod 0 light machine gun fielded in limited numbers by US Navy SEALs in Vietnam.
Specifications
| Weight (empty) | 5310 g (187.3 oz) |
| Overall Length | 1020 mm (40.16") |
| Barrel Length | 508 mm (20.00") |
| Action Type | Gas Operated Long Stroke |
| Firing Mechanism | Hammer Fired |
| Trigger Type | Single Stage |
| Magazine Capacity | 30 rounds |
| Magazine Type | Belt |
| Muzzle Velocity | 991 m/s (3251 fps) |
| Muzzle Energy | 1748 J (1289 ft·lbf) |
| Effective Range | 549 m (600 yd) |
| Maximum Range | 2655 m (2904 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 · M193 — also known as 5.56mm, .223 Remington (parent)
Features
- Firing modes: Full Automatic
- Feed systems: Detachable Box Magazine, Disintegrating Belt
- Safety mechanisms: Manual Safety, Trigger Guard Safety Lever
- Features: Modular Weapon System, Belt Fed, Magazine Fed, Quick Change Barrel, Convertible Configuration, Rotating Bolt, Stainless Steel Gas Tube, Bipod
Variants
- Stoner 63A Commando — Carbine Configuration
- Stoner 63A Mk 23 Mod 0 — Lmg Configuration
Base model
Service history
Operators
- United States Navy SEALs · adopted 1967 · as Mk 23 Mod 0
- United States Army Special Forces · adopted 1970 · as XM207
- United States Marine Corps · as XM22 / XM23
Conflicts
- Vietnam War (1955-1975)
Production
Estimated total produced: 4,000 · Production years: 1963-1971
Approximate total across all configurations of the Stoner 63/63A system; figures disputed
Origin
Country of origin: United States
Designer: Eugene Stoner
Discontinued: 1971
Notes
Despite its engineering brilliance the Stoner 63 system was complex, maintenance-intensive, and dirt-sensitive, which prevented wide adoption. The belt-fed Commando LMG configuration was prized by SEALs for its firepower-to-weight ratio.
Background
Designed by the same Eugene Stoner who created the AR-15/M16, the Stoner 63 was arguably the first truly modular small-arms system, a kit of about fifteen interchangeable subassemblies that one armorer could rebuild from carbine to belt-fed machine gun in minutes.