BRN-180S® Gen2 – Now with 300 Blackout Configuration! Designed in conjunction with PWS & FM Products, the Brownells BRN-180S® Complete Upper Receiver is the newest iteration of the BRN-180® Upper Receiver, which was inspired by the Armalite® AR-180 of the 1960s. The BRN-180S® shares a large chunk of components with the BRN-180®, but introduces key features to improve reliability and usability in a short configuration. The BRN-180S® is obviously shorter than the standard BRN-180®. The 300 Blackout required a shorter system to ensure reliability with a wide variety of supersonic and subsonic ammunition. This resulting shorter system also required a cutout in the handguard to access the two-position adjustment. The user can select between these two settings to find the most reliable configuration with their ammo and suppressor. The BRN-180® Gen2 Upper Receiver Group improves upon the original BRN-180® with two main upgrades. First, all BRN-180® Upper Receivers now ship with an Adjustable Gas System, previously only found on the BRN-180S®. The operating mechanism, the short stroke gas piston concept remains the same, but the user can select between two settings, depending on their conditions and ammunition, to ensure smooth and consistent function. No more spare gas piston cup to worry about. In addition to the new Adjustable Gas System, the Handguard is now retaining with a single locking screw. This large screw provides ample locking force and ensures a more consistent handguard lockup than the previous mechanism. During extended firing, and the barrel heating up, this new locking system ensures the handguard retains alignment and rigidity with the upper receiver. Also, with this new takedown mechanism, the handguard can be removed to access the gas system without removing the internal components. Weight: 3 lbs 10 oz Like the original AR-180, the BRN-180® bolt carrier rides smoothly on a PAIR of guide rods. The carrier is buffered at the rear by a built-in polymer buffer with a molded-in steel plate that captures the guide rods. The Nitride bolt replicates the original AR-180 bolt design, right down to its use of a standard AR-15 extractor. The barrel is machined from extra-strong 4150 carbon steel, with a hard Nitride finish that really resists surface wear. The 300 Blackout BRN-180® also features a 1-8 twist for a wide variety of ammo usage. Up front there's a replica of the AR-180's unusual three-prong flash hider: the hemispherical bottom prong helps prevent the muzzle blast from kicking up a dust signature when shooting prone. Standard 5/8-24 tpi muzzle threads let you swap on a modern AR-15 muzzle device should you be bitten by the customizing bug.
- Ultra-reliable AR-180™ piston operating system
- Compatible with current mil-spec AR-15 lowers
- Machined 7075 T6 aluminum receiver & handguard - hardcoat anodized finish
- 10” on 300 Blackout with matte black Nitride finish
- 300 AAC Blackout chamber
- Button rifled bore; 1-8"" twist 300 Blackout
- 5/8-24 for 300 Blackout
- Replica 3-prong AR-180™ flash suppressor
- Molded polymer ejection port cover
- Total weight: 4 lbs
Big Book Catalog, Issue:73, Page:002
For Silencer or New Muzzle Device Installation:
1. To Remove Flash Hider
Turn jam nut clockwise, as if looking at the muzzle, to loosen from the flash hider.
Unscrew flash hider from muzzle by turning counterclockwise.
2. Tighten the jam nut, turning clockwise, against the “C” clip/shoulder.
Do not remove the “C” clip from under the jam nut or the jam nut. Doing so could induce misalignment and cause suppressor damage. The jam nut must remain tight against the “C” clip/shoulder
3. Install muzzle device or suppressor to the factory recommended specs.
If using a muzzle device that requires to be indexed to a specific position, use muzzle shims, 084-000-460, to obtain the proper index with the torque specified by the manufacture.
i. Do Not use the jam nut to secure the muzzle device or suppressor in place. This could cause misalignment and possibly damage the suppressor
DO NOT ALIGN THE DEVICE BY HAND AND USE THE JAM NUT TO SECURE IN PLACE. This could cause misalignment and possibly damage the suppressor.
4. Brownells recommends checking the suppressor with an alignment rod to insure proper alignment of the suppressor to the bore.