BRN-4 COMPLETE UPPER RECEIVERS
Assembled from All New Components, Now with Handguard and Muzzle Device
The BRN-4® Upper Receiver is now available as a Complete Upper, with Handguard, Muzzle Device, Barrel and Gas System installed. Simply attach to your AR-15 lower receiver and you’re ready to hit the range!
These complete uppers have the option of shipping with a shorter barrel configuration, with a 9 inch Midwest Industries handguard, or on the longer length barrel models, a 13.5 inch Midwest Industries handguard. The handguards feature plentiful MLOK attachment point, as well as a full length picatinny rail.
Built from the ground up, the core of the BRN-4® Upper Receiver is an all new Bolt Carrier Group, featuring a phosphate carrier and a chrome bolt. 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 new BRN-4® barrel, produced by Faxon®, is available in a variety of profiles and lengths to suit your needs. Barrels are chambered 5.56x45mm NATO, are button rifled with a 1-7 twist, 1/2-28 muzzle and come with the appropriate gas block for a given barrel length. Barrels are available in a medium or heavy profile. The heavy profile ensures a rigid and robust platform for precision shooting. The medium profile balances the desire to have a lighter piston configuration, while still having plenty of barrel material to prevent drifting of grouping as the barrel heats.
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 ensure that the barrel is rigidly mounted with the pre-installed barrel nut. Barrel nut is torqued properly with AeroShell Grease 64 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.
Brownells recommends an H1 or H2 recoil buffer with carbine recoil spring for optimal operation.
*** Brownells recommends use of 5.56x45mm NATO newly manufactured quality ammunition 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.
ALL NFA RULES APPLY.
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