Brownells BRN-180
- Category
- Rifle
- Barrel
- 406 mm
- Weight, empty
- Not recorded
- Introduced
- 2018
About
What it is, and why it matters
The Brownells BRN-180 is a modern reimagining of the ArmaLite AR-180, built as a complete AR-15-pattern upper receiver assembly. Unlike a standard AR-15, it uses a short-stroke gas piston operating system fully contained within the receiver, eliminating the need for a buffer, recoil spring, and receiver extension. This bufferless design, combined with a reciprocating side charging handle, allows a true side-folding stock to be fitted to a compatible lower. Barrels are button-rifled 4150 carbon steel with a nitride finish and a 1:8 twist, and the rifle-length 5.56 configuration uses a 16-inch barrel with a retro three-prong flash hider.
The BRN-180 revives Eugene Stoner's AR-18/AR-180 short-stroke piston design from the 1960s, the same operating system that influenced rifles like the HK G36, SA80, and modern AR pistons - now repackaged as a bufferless, folding-stock-capable upper for the AR-15 lower.
Sold primarily as a complete upper receiver assembly that mounts on a standard AR-15 lower; chambered in .223 Wylde to feed both 5.56 NATO and .223 Remington. Also offered in .300 Blackout and 7.62x39mm, and in pistol/carbine/rifle barrel lengths. Developed in collaboration with PWS and FM Products. Complete-rifle weight varies by lower and barrel length.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- Brownells
- Category
- Rifle
- Country
- United States
- Status
- In production
- Produced
- 2018
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 406 mm
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Gas operated short stroke
- 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
- Aluminum
- Barrel
- Steel
- Stock
- Polymer
- Finish
- Nitride
BallisticsFrom the service cartridge, not a handload.
- Effective range
- 500 m
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.
Short stroke gas piston
Adjustable gas block- Bufferless operation
Side charging handle
Folding stock capable
Free floating handguard
M lok handguard
Three prong flash hider
Nitride barrel
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 |
|---|---|---|---|
| Barrel lengthAmong 98 5.56x45mm NATO rifles | 406 mm | 406 mm | Shorter than about 60% |
| Magazine capacityAmong 98 5.56x45mm NATO rifles | 30 | 30 | Near the median |
Answers
Questions about the Brownells BRN-180
What caliber is the Brownells BRN-180?
The Brownells BRN-180 is chambered in 5.56x45mm NATO.
How many rounds does the Brownells BRN-180 hold?
The Brownells BRN-180 holds 30 rounds, fed from a detachable box magazine.
How long is the Brownells BRN-180?
The Brownells BRN-180 has a 406 mm (16.0 in) barrel.
Who makes the Brownells BRN-180?
The Brownells BRN-180 is made by Brownells (United States).
When was the Brownells BRN-180 introduced?
The Brownells BRN-180 was introduced in 2018.
How does the Brownells BRN-180 operate?
The Brownells BRN-180 uses a gas operated short 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.
Provenance
Confidence in this record
70%
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/brn-180' \ --header 'X-API-Key: your_key'{ "id": "brn-180", "name": "Brownells BRN-180", "manufacturer": { "id": "brownells", "name": "Brownells", "countryCode": "US", "foundedYear": 1939, "website": "https://www.brownells.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": "d64a70268fda69e5afd33ecc273eee3b08d44df4568f64b0c12a46b32f248f91" }, "category": { "id": "rifle", "name": "Rifle", "description": "Long-barreled firearms designed for accurate shooting" }, "country_of_origin": "US", "year_introduced": 2018, "barrel_length_mm": 406, "weight_empty_g": null, "action_type": "gas_operated_short_stroke"}