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Brownells
The Brownells BRN-15 5.56mm upper receiver with 13.7" barrel and .750" gas block is a US-manufactured upper assembly built for shooters who want a complete, ready-to-pair platform without assembling from loose parts. This forged upper comes with a nitride-finished 4150 CMV barrel, M4 feed ramps, ejection port cover, and forward assist—everything you need except a bolt carrier group and charging handle. It's ideal for AR builders and gunsmiths looking to start with a proven, American-made foundation.
The 13.7" barrel is threaded 1/2-28 and ships with an A2 flash hider, tuned for 5.56 NATO with a 1:7 twist rate suited to a wide range of bullet weights. The .750" gas block mounting surface (dimpled for secure screw engagement) keeps the gas system reliable and repeatable. Stress-relieved barrel construction helps maintain accuracy over time and thermal cycles.
The handguard is where Brownells made smart design choices: it's M-LOK compatible, extends past the gas block to maximize mounting real estate, and features anti-rotation tabs that lock it to the upper receiver's Picatinny rail—no cant, no surprises. Large dual screws clamp through a properly torqued barrel nut, preventing creep. Strategic cooling vents near the rear let both barrel and handguard shed heat quickly during extended shooting sessions.
The forged 7075-T6 upper receiver is hardcoat anodized to Mil-Spec standards, with a knurled forward assist pin for easy future swaps. This is a no-compromise, no-frills assembly: 100% US-made components, marked and documented, ready to marry to your choice of BCG and charging handle.
| Caliber | 5.56x45mm NATO |
| Barrel Length | 13.7" |
| Barrel Material | 4150 CMV steel, nitride finished |
| Twist Rate | 1:7 |
| Gas Block Size | .750" |
| Muzzle Thread | 1/2-28 |
| Muzzle Device | A2 flash hider |
| Upper Receiver Material | Forged 7075-T6 aluminum, hardcoat anodized |
| Handguard Type | M-LOK |
| Feed Ramps | M4 (upper and barrel extension) |
| Country of Origin | USA |
This upper assembly does not include a bolt carrier group or charging handle. You'll need to source and install both to have a functional rifle. Once paired with those components and a lower receiver, you'll have a complete rifle.
Yes. This is a forged Mil-Spec upper receiver that mates to standard AR-15 lower receivers with conventional takedown pins and trigger groups.
The upper features a M-LOK compatible handguard with anti-rotation tabs that lock into the receiver's Picatinny rail, eliminating cant. The handguard extends past the gas block and includes venting for cooling.
Yes. The muzzle is threaded 1/2-28. Note: the 16" lightweight model includes a lock nut on the flash hider; to remove it, secure the lock nut with a wrench, turn toward the rear, and unscrew the flash hider.
Brownells
The Brownells BRN-15 5.56mm upper receiver with 13.7" barrel and .750" gas block is a US-manufactured upper assembly built for shooters who want a complete, ready-to-pair platform without assembling from loose parts. This forged upper comes with a nitride-finished 4150 CMV barrel, M4 feed ramps, ejection port cover, and forward assist—everything you need except a bolt carrier group and charging handle. It's ideal for AR builders and gunsmiths looking to start with a proven, American-made foundation.
The 13.7" barrel is threaded 1/2-28 and ships with an A2 flash hider, tuned for 5.56 NATO with a 1:7 twist rate suited to a wide range of bullet weights. The .750" gas block mounting surface (dimpled for secure screw engagement) keeps the gas system reliable and repeatable. Stress-relieved barrel construction helps maintain accuracy over time and thermal cycles.
The handguard is where Brownells made smart design choices: it's M-LOK compatible, extends past the gas block to maximize mounting real estate, and features anti-rotation tabs that lock it to the upper receiver's Picatinny rail—no cant, no surprises. Large dual screws clamp through a properly torqued barrel nut, preventing creep. Strategic cooling vents near the rear let both barrel and handguard shed heat quickly during extended shooting sessions.
The forged 7075-T6 upper receiver is hardcoat anodized to Mil-Spec standards, with a knurled forward assist pin for easy future swaps. This is a no-compromise, no-frills assembly: 100% US-made components, marked and documented, ready to marry to your choice of BCG and charging handle.
| Caliber | 5.56x45mm NATO |
| Barrel Length | 13.7" |
| Barrel Material | 4150 CMV steel, nitride finished |
| Twist Rate | 1:7 |
| Gas Block Size | .750" |
| Muzzle Thread | 1/2-28 |
| Muzzle Device | A2 flash hider |
| Upper Receiver Material | Forged 7075-T6 aluminum, hardcoat anodized |
| Handguard Type | M-LOK |
| Feed Ramps | M4 (upper and barrel extension) |
| Country of Origin | USA |
This upper assembly does not include a bolt carrier group or charging handle. You'll need to source and install both to have a functional rifle. Once paired with those components and a lower receiver, you'll have a complete rifle.
Yes. This is a forged Mil-Spec upper receiver that mates to standard AR-15 lower receivers with conventional takedown pins and trigger groups.
The upper features a M-LOK compatible handguard with anti-rotation tabs that lock into the receiver's Picatinny rail, eliminating cant. The handguard extends past the gas block and includes venting for cooling.
Yes. The muzzle is threaded 1/2-28. Note: the 16" lightweight model includes a lock nut on the flash hider; to remove it, secure the lock nut with a wrench, turn toward the rear, and unscrew the flash hider.
