Assembled from All New Components – Now with Chrome Lined Barrels

The BRN-4® Upper Receiver is now available as an Assembled Upper, with Barrel and Gas System installed. Simply add your preferred HK® 416 compatible handguard and any 1/2-28 muzzle device, and you’re ready to hit the range!

Chrome lined bore and chamber of these barrels has been the go-to for hard use rifle barrels for decades, and you will be extremely pleased with the smooth and crisp application by Faxon in these bores. The chrome is well applied, and just extends over the crown of the barrel and the edge of the chamber. These medium profile barrels are made by Faxon, who button rifles from 4150 chrome moly steel, the top choice for hard use barrels. The 1:7 twist accommodate heavy projectiles and the barrels feature ½-28 muzzle threads for the attachment of the muzzle device of your choice. A matte black phosphate provides a corrosion resistant exterior.

Built from the ground up, the core of the BRN-4® Upper Receiver is an all new Bolt Carrier Group, featuring a slick nitride finish. The carrier itself is machined from one piece of forged 8620 steel. The bolt is precision machined from 9310 tool steel and headspaced prior to and after barrel installation.

The upper receiver utilized in this assembly is made completely new, from billet, to mirror the profiles commonly found on forged upper receivers. Contours of the upper are entirely machined from billet, so rounded areas such as the cam pin protrusion and complex contours will show machine passes more prominently. The machined upper is finished with matte black hard coat anodizing. The proper piston bushing is installed to eliminate any piston wear on the aluminum part, and is secured in place with blue threadlocker. The BRN-4® features much longer barrel nut threads, engaging the barrel extension over a much larger surface area than a standard AR-15. This ensures that the barrel is rigidly mounted with the pre-installed barrel nut. Barrel nut is torqued properly with Brownells Copper Anti-Sieze (graphite free) applied to the upper receiver threads. The barrel nut is reinstalled 3 times to ensure an accurate torque spec is achieved.

Gas blocks are vented forward, to reduce gas sent rearward into the system, and are mated specific to the 10.4 or 14.5/16 inch barrel lengths.

Upper includes Magpul ejection port cover and mil-spec charging handle.

Handguard installation is extremely simple, just slide handguard over the barrel and tighten one bolt. Be sure to follow any specific instructions advised by the manufacturer.

Muzzle devices installation is also straightforward, as the barrel is 1/2-28 and the BRN-4 upper is compatible with common upper receiver “rods” and jigs. Any AR-15 1/2-28 muzzle device will be compatible.

Brownells recommend H1 or H2 recoil buffer with carbine recoil spring for optimal operation.

All BRN-4 Upper Receiver Assemblies are test fired before final packaging. Upper may display signs of firing, such as brass marks on the shell deflector or slight fouling inside.

Cartridge : 5.56 x 45
Color : Black
Contour : Medium
Finish : Manganese Phosphate
Length : 23.5''
Make : Brownells
Make/Model : BRN-4
Model : BRN-4
Twist : 1:7