XM19 SPIW
- Category
- Assault Rifle
- Barrel
- 559 mm
- Weight, empty
- 2.88 kg
- Introduced
- 1964
About
What it is, and why it matters
The XM19 SPIW is an experimental American flechette-firing assault rifle developed by AAI Corporation under the U.S. Army's Special Purpose Individual Weapon (SPIW) program during the 1960s and early 1970s. It fired a fin-stabilized 5.6mm flechette dart from a smoothbore barrel at extremely high velocity, and offered a very high cyclic rate of fire intended to improve hit probability in burst fire. Like other SPIW entrants, the XM19 was paired with an integral multi-shot grenade launcher. Despite years of development, persistent problems with flechette accuracy, dispersion, and cost meant the program never produced a service weapon, and the XM19 remained a prototype.
The SPIW program embodied the U.S. Army's 1960s belief that the future of small arms lay in salvo and flechette fire rather than conventional bullets. The tiny tungsten or steel darts flew flat and fast, but proved difficult to manufacture cheaply and to stabilize accurately, and the rifles became heavy and complex once a grenade launcher was bolted on.
Part of the long-running SPIW program that sought to replace the M16 with a flechette weapon. The flechette ammunition went through several iterations (XM110, XM144, XM645). The program's failure to deliver a practical flechette rifle later fed into the ACR (Advanced Combat Rifle) effort of the 1980s.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- AAI Corporation (Textron Systems)
- Category
- Assault Rifle
- Country
- United States
- Status
- Prototype
- Produced
- 1964 to 1974
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 559 mm
- Overall length
- 940 mm
- Weight, empty
- 2.88 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Gas operated
- Firing mechanism
- Hammer fired
- Trigger
- Single stage
- Capacity
- 60
- Magazine
- Detachable box
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
- 1402 m/s
- Muzzle energy
- 648 J
- Effective range
- 400 m
- Rate of fire
- 2200 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.
No load solved for this record yetThe flight path is computed from a cartridge and a bullet. This record has no ammunition filed against its chambering, so there is nothing to solve.
Features
What it has
What the record lists as fitted, drawn from the catalogue.
Flechette ammunition
Smoothbore barrel
Integral grenade launcher- Burst fire
- High cyclic rate
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 274 assault rifles | 2.88 kg | 3.59 kg | Lighter than about 90% |
| Overall lengthAmong 271 assault rifles | 940 mm | 915 mm | Longer than about 60% |
| Barrel lengthAmong 271 assault rifles | 559 mm | 415 mm | Longer than about 90% |
| Magazine capacityAmong 276 assault rifles | 60 | 30 | Among the largest capacities |
Answers
Questions about the XM19 SPIW
How much does the XM19 SPIW weigh?
The XM19 SPIW weighs 2.88 kg (6.35 lb) empty.
What caliber is the XM19 SPIW?
The XM19 SPIW is chambered in 5.6mm Flechette.
How many rounds does the XM19 SPIW hold?
The XM19 SPIW holds 60 rounds, fed from a detachable box magazine.
How long is the XM19 SPIW?
The XM19 SPIW is 940 mm (37.0 in) long overall, with a 559 mm (22.0 in) barrel.
Who makes the XM19 SPIW?
The XM19 SPIW is made by AAI Corporation (Textron Systems) (United States). It was designed by AAI Corporation.
When was the XM19 SPIW introduced?
The XM19 SPIW was introduced in 1964 and discontinued in 1974.
How does the XM19 SPIW operate?
The XM19 SPIW uses a gas operated 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 Army
- United States
Provenance
Confidence in this record
55%
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/xm19-spiw' \ --header 'X-API-Key: your_key'{ "id": "xm19-spiw", "name": "XM19 SPIW", "manufacturer": { "id": "aai-corporation", "name": "AAI Corporation (Textron Systems)", "countryCode": "US", "foundedYear": 1950, "website": "https://www.textronsystems.com", "logoUrl": null, "description": null, "status": null, "defunctYear": null, "stateOwned": null, "makesFirearms": null, "parentId": null, "predecessorId": null, "createdAt": "2026-06-21 23:00:46", "updatedAt": "2026-06-21 23:00:46", "version": "e5da025c597cd46db144f928652cc8a4086810da5d7e7cc7b5faa3f2288277ca" }, "category": { "id": "assault-rifle", "name": "Assault Rifle", "description": "Selective-fire rifles chambered in intermediate cartridges" }, "country_of_origin": "US", "year_introduced": 1964, "barrel_length_mm": 559, "weight_empty_g": 2880, "action_type": "gas_operated"}