Brownells194200218
Brownells Brn-4 5.56Mm 14.5'' Med Bbl Complete Upper W/13.5'' Handguard$1,218.74
Availability: In Stock
Current Stock: Out of stock
The Brownells BRN-4 5.56mm complete upper receiver with 14.5" heavy barrel and 13.5" handguard is a no-compromise build platform designed for shooters who want a factory-assembled, precision-ready upper that simply bolts onto an AR-15 lower. If you're tired of sourcing individual components and piecing together an upper, this is the answer—everything you need arrives tested, headspaced, and ready to run.
Built from the ground up with all-new components, the BRN-4 starts with a Faxon barrel in 5.56x45mm NATO with a 1-7 twist and 1/2-28 muzzle. The heavy profile keeps shots tight even when the barrel heats up during extended range sessions, making this a solid choice for precision work or competitive shooting. The bolt carrier group features a nitride-finished carrier machined from forged 8620 steel and a bolt precision-finished from 9310 tool steel—both headspaced before and after barrel installation to guarantee reliability. The billet upper receiver is machined to mirror standard forged profiles, finished in matte black hard coat anodize, and fitted with an oversized barrel nut that threads deep into the barrel extension for rock-solid rigidity. Brownells torques this barrel nut three times to spec and applies AeroShell Grease 64 for longevity.
The 13.5" Midwest Industries handguard features full M-LOK and picatinny rail coverage, giving you abundant mounting real estate for lights, lasers, grips, and whatever else your setup demands. The gas block is vented forward to minimize backpressure, and a Magpul ejection port cover and mil-spec charging handle round out the package. Every upper is test-fired before shipment, so minor brass marks or light fouling is normal. Pair this with an H1 or H2 buffer and carbine spring on your lower, load quality 5.56 ammo, and get to work.
| Caliber | 5.56x45mm NATO |
| Barrel Length | 14.5" |
| Barrel Profile | Heavy |
| Barrel Rifling | Button rifled, 1-7 twist |
| Muzzle Thread | 1/2-28 |
| Handguard | 13.5" Midwest Industries |
| Handguard Attachments | M-LOK and full picatinny rail |
| Upper Receiver Material | Billet aluminum |
| Upper Receiver Finish | Matte black hard coat anodize |
| Bolt Carrier Group | Nitride finished; carrier forged 8620 steel, bolt 9310 tool steel |
| Charging Handle | Mil-spec |
| Includes | Magpul ejection port cover, muzzle device |
You'll need an AR-15 lower receiver, plus an H1 or H2 recoil buffer and a carbine recoil spring to pair with this upper. Once mated to your lower, you're ready to run.
Yes—the upper arrives fully assembled, test-fired, and ready to attach to your lower. It may show minor brass marks or light fouling from factory testing, which is normal and harmless.
Brownells recommends quality newly manufactured 5.56x45mm NATO ammunition for optimal operation. Headspacing has been verified before and after barrel installation.
The extended barrel nut threads deep into the barrel extension, creating a much larger contact surface than a standard AR-15 barrel nut. This ensures the barrel is mounted with maximum rigidity and consistent torque specs—Brownells torques it three times during assembly to get it right.
SKU: 194200225 • Weight: 7oz
Availability: In Stock
Current Stock: Out of stock
The Brownells BRN-4 5.56mm complete upper receiver with 14.5" heavy barrel and 13.5" handguard is a no-compromise build platform designed for shooters who want a factory-assembled, precision-ready upper that simply bolts onto an AR-15 lower. If you're tired of sourcing individual components and piecing together an upper, this is the answer—everything you need arrives tested, headspaced, and ready to run.
Built from the ground up with all-new components, the BRN-4 starts with a Faxon barrel in 5.56x45mm NATO with a 1-7 twist and 1/2-28 muzzle. The heavy profile keeps shots tight even when the barrel heats up during extended range sessions, making this a solid choice for precision work or competitive shooting. The bolt carrier group features a nitride-finished carrier machined from forged 8620 steel and a bolt precision-finished from 9310 tool steel—both headspaced before and after barrel installation to guarantee reliability. The billet upper receiver is machined to mirror standard forged profiles, finished in matte black hard coat anodize, and fitted with an oversized barrel nut that threads deep into the barrel extension for rock-solid rigidity. Brownells torques this barrel nut three times to spec and applies AeroShell Grease 64 for longevity.
The 13.5" Midwest Industries handguard features full M-LOK and picatinny rail coverage, giving you abundant mounting real estate for lights, lasers, grips, and whatever else your setup demands. The gas block is vented forward to minimize backpressure, and a Magpul ejection port cover and mil-spec charging handle round out the package. Every upper is test-fired before shipment, so minor brass marks or light fouling is normal. Pair this with an H1 or H2 buffer and carbine spring on your lower, load quality 5.56 ammo, and get to work.
| Caliber | 5.56x45mm NATO |
| Barrel Length | 14.5" |
| Barrel Profile | Heavy |
| Barrel Rifling | Button rifled, 1-7 twist |
| Muzzle Thread | 1/2-28 |
| Handguard | 13.5" Midwest Industries |
| Handguard Attachments | M-LOK and full picatinny rail |
| Upper Receiver Material | Billet aluminum |
| Upper Receiver Finish | Matte black hard coat anodize |
| Bolt Carrier Group | Nitride finished; carrier forged 8620 steel, bolt 9310 tool steel |
| Charging Handle | Mil-spec |
| Includes | Magpul ejection port cover, muzzle device |
You'll need an AR-15 lower receiver, plus an H1 or H2 recoil buffer and a carbine recoil spring to pair with this upper. Once mated to your lower, you're ready to run.
Yes—the upper arrives fully assembled, test-fired, and ready to attach to your lower. It may show minor brass marks or light fouling from factory testing, which is normal and harmless.
Brownells recommends quality newly manufactured 5.56x45mm NATO ammunition for optimal operation. Headspacing has been verified before and after barrel installation.
The extended barrel nut threads deep into the barrel extension, creating a much larger contact surface than a standard AR-15 barrel nut. This ensures the barrel is mounted with maximum rigidity and consistent torque specs—Brownells torques it three times during assembly to get it right.
SKU: 194200225 • Weight: 7oz