Brownells BRN-180
Brownells · Rifle · In Production · 2018
Also known as: BRN-180, BRN-180 Gen 2
Overview
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.
Specifications
| Barrel Length | 406 mm (15.98") |
| Action Type | Gas Operated Short Stroke |
| Firing Mechanism | Hammer Fired |
| Trigger Type | Single Stage |
| Magazine Capacity | 30 rounds |
| Magazine Type | Detachable Box |
| Effective Range | 500 m (547 yd) |
| Barrel Rifling | Right Hand |
| Rifling Twist | 203 mm (7.99") |
| Frame Material | Aluminum |
| Barrel Material | Steel |
| Stock Material | Polymer |
| Finish | Nitride |
Calibers
- 5.56x45mm NATO · primary · 5.56x45mm NATO — also known as .223 Remington, 5.56 NATO, .223 Wylde
Features
- Firing modes: Semi Automatic
- Feed systems: Detachable Box Magazine
- Safety mechanisms: Manual Safety
- Features: 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
Production
Production years: 2018-present
Civilian-market upper receiver assembly; Gen 2 introduced 2020
Origin
Country of origin: United States
Notes
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.
Background
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.