AAI ACR
- Category
- Assault Rifle
- Barrel
- 508 mm
- Weight, empty
- 3.53 kg
- Introduced
- 1989
About
What it is, and why it matters
The AAI ACR is a prototype flechette-firing assault rifle developed by the AAI Corporation for the United States Army's Advanced Combat Rifle (ACR) program of 1989-1990. Building on the company's earlier SPIW and XM19 serial-flechette work, it fired a saboted 1.6mm fin-stabilized steel flechette packaged in a 5.56x45mm brass case at roughly 1,400 m/s, giving an extremely flat trajectory and very low recoil impulse. A gas-operated three-chamber breech allowed a high-cyclic three-round burst, while a proprietary magazine and altered magazine well prevented the accidental loading of standard 5.56mm NATO ammunition. Like the other ACR entrants, it failed to demonstrate the required 100 percent hit-probability improvement over the M16A2 and was not adopted.
The AAI ACR was the culmination of decades of US flechette-rifle research that began with the Special Purpose Individual Weapon (SPIW) program and the XM19 serial flechette rifle. Its dart-like projectile flew so fast and flat that AAI's entry was praised for flechette reliability, yet the whole ACR program ended without a winner because no design could beat the M16A2 by the required margin.
Cyclic rate within the three-round burst was approximately 1,800 rpm; sustained semi-automatic fire was also possible. The flechette weighed about 0.66 g, with the full sabot-and-flechette assembly around 1.36 g.
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
- 1989 to 1990
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 508 mm
- Overall length
- 1016 mm
- Weight, empty
- 3.53 kg
- Weight, loaded
- 4.26 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Gas operated
- Firing mechanism
- Hammer fired
- Trigger
- Single stage
- Capacity
- 30
- Magazine
- Detachable box
MaterialsEach swatch is the material itself, not a colour chosen to stand for it.
- Frame
- Steel
- Barrel
- Steel
- Stock
- Polymer
- Finish
- Phosphate
BallisticsFrom the service cartridge, not a handload.
- Muzzle velocity
- 1402 m/s
- Muzzle energy
- 649 J
- Effective range
- 610 m
- Rate of fire
- 1800 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.
Three chamber breech
Saboted flechette ammunition
Proprietary magazine well
Detachable 4x optic
Iron sights- Low recoil impulse
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 | 3.53 kg | 3.59 kg | Near the median |
| Overall lengthAmong 271 assault rifles | 1016 mm | 915 mm | Longer than about 90% |
| Barrel lengthAmong 271 assault rifles | 508 mm | 415 mm | Longer than about 90% |
| Magazine capacityAmong 276 assault rifles | 30 | 30 | Holds more rounds than about 60% |
Answers
Questions about the AAI ACR
How much does the AAI ACR weigh?
The AAI ACR weighs 3.53 kg (7.78 lb) empty and 4.26 kg (9.39 lb) loaded.
What caliber is the AAI ACR?
The AAI ACR is chambered in 5.56mm Flechette.
How many rounds does the AAI ACR hold?
The AAI ACR holds 30 rounds, fed from a detachable box magazine.
How long is the AAI ACR?
The AAI ACR is 1016 mm (40.0 in) long overall, with a 508 mm (20.0 in) barrel.
Who makes the AAI ACR?
The AAI ACR is made by AAI Corporation (Textron Systems) (United States). It was designed by AAI Corporation.
When was the AAI ACR introduced?
The AAI ACR was introduced in 1989 and discontinued in 1990.
How does the AAI ACR operate?
The AAI ACR 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
78%
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/aai-acr' \ --header 'X-API-Key: your_key'{ "id": "aai-acr", "name": "AAI ACR", "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": 1989, "barrel_length_mm": 508, "weight_empty_g": 3530, "action_type": "gas_operated"}