Stoner 63A
- Category
- Machine Gun
- Barrel
- 508 mm
- Weight, empty
- 5.31 kg
- Introduced
- 1966
About
What it is, and why it matters
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.
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.
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.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- Cadillac Gage
- Category
- Machine Gun
- Country
- United States
- Status
- Discontinued
- Produced
- 1966 to 1971
- Variant of
- Improved model
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 508 mm
- Overall length
- 1020 mm
- Weight, empty
- 5.31 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Gas operated long stroke
- Firing mechanism
- Hammer fired
- Trigger
- Single stage
- Capacity
- 30
- Magazine
- Belt
MaterialsEach swatch is the material itself, not a colour chosen to stand for it.
- Frame
- Steel
- Barrel
- Steel
- Stock
- Polymer
- Finish
- Parkerized
BallisticsFrom the service cartridge, not a handload.
- Muzzle velocity
- 991 m/s
- Muzzle energy
- 1748 J
- Effective range
- 549 m
- Maximum range
- 2655 m
- Rate of fire
- 700 rpm
Trajectory
What the round does downrange
Solved from the muzzle figures and the bullet. The dashed rule is the effective range on the record, and the crosses are the steps the solver returned.
Features
What it has
What the record lists as fitted, drawn from the catalogue.
- Modular weapon system
Belt fed
Magazine fed
Quick change barrel- Convertible configuration
Rotating bolt
Stainless steel gas tube
Bipod
Standing
How it compares
Each figure against the firearms of the same type and cartridge that record it, or of the same type where that cartridge has too few. Positions are read to the nearest tenth.
| Measurement | This firearm | Median | Position |
|---|---|---|---|
| Empty weightAmong 27 5.56x45mm NATO machine guns | 5.31 kg | 6.35 kg | Lighter than about 60% |
| Overall lengthAmong 25 5.56x45mm NATO machine guns | 1020 mm | 1020 mm | Near the median |
| Barrel lengthAmong 26 5.56x45mm NATO machine guns | 508 mm | 465 mm | Longer than about 80% |
| Magazine capacityAmong 26 5.56x45mm NATO machine guns | 30 | 200 | Among the smallest capacities |
Answers
Questions about the Stoner 63A
How much does the Stoner 63A weigh?
The Stoner 63A weighs 5.31 kg (11.71 lb) empty.
What caliber is the Stoner 63A?
The Stoner 63A is chambered in 5.56x45mm NATO.
How many rounds does the Stoner 63A hold?
The Stoner 63A holds 30 rounds, fed from a belt.
How long is the Stoner 63A?
The Stoner 63A is 1020 mm (40.2 in) long overall, with a 508 mm (20.0 in) barrel.
Who makes the Stoner 63A?
The Stoner 63A is made by Cadillac Gage (United States). It was designed by Eugene Stoner.
When was the Stoner 63A introduced?
The Stoner 63A was introduced in 1966 and discontinued in 1971.
How does the Stoner 63A operate?
The Stoner 63A uses a gas operated long stroke action, and its firing mechanism is hammer fired.
Compatibility
Which parts fit this firearm
Studio
Every part that mounts on this, resolved
Not a list the maker typed out: the answer comes from the mounts this firearm exposes and the interface each part needs, so it stays right when either one changes.
- Every part that mounts on any firearm in the catalogue
- Interface standards, platforms and fit overrides
- The same answers through the API and the MCP server
Requires a signed-in GunSpec account on the Studio plan. The answer is computed per part, so it is not part of the public record.
Provenance
What the record holds
Every figure above was taken from one of these pages. The confidence reflects how much of the record came from a page a claim can be checked against.
In service
- United States Navy SEALs
- 1967
- United States Army Special Forces
- 1970
- United States Marine Corps
- United States
Provenance
Confidence in this record
75%
Stockists
Where to buy
Offers link straight to the shop. GunSpec never takes the order.
No shop has listed this firearm yet
Stock and prices come from the shops themselves. If you sell this firearm, you can list it and it appears here.
List a firearmMCP
Ask an assistant about it
The same record, reached the way a person asks for it rather than the way a program does.
Ask GunSpec
Works with
Point an MCP client at GunSpec and it answers from the catalogue rather than from memory. A free key covers the read tools.
API
The call that returns this record
The same fields, in the same units, from the same endpoint the page reads.
curl --request GET \ --url 'https://api.gunspec.io/v1/firearms/stoner-63a' \ --header 'X-API-Key: your_key'{ "id": "stoner-63a", "name": "Stoner 63A", "manufacturer": { "id": "cadillac-gage", "name": "Cadillac Gage", "countryCode": "US", "foundedYear": 1950, "website": null, "logoUrl": null, "description": null, "status": "defunct", "defunctYear": null, "stateOwned": null, "makesFirearms": null, "parentId": null, "predecessorId": null, "createdAt": "2026-04-26 23:12:00", "updatedAt": "2026-04-26 23:12:00", "version": "fd8350dec821e0d413724228265c9acd09c2790b2bc0315f848441fc904d6196" }, "category": { "id": "machine-gun", "name": "Machine Gun", "description": "Fully automatic firearms for sustained fire" }, "country_of_origin": "US", "year_introduced": 1966, "barrel_length_mm": 508, "weight_empty_g": 5310, "action_type": "gas_operated_long_stroke"}