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, with a 10.5 inch barrel. The free float M-LOK handguard mated to the assembly is also shorter, terminating just in front the gas block. The gas block is where the large differences are between the prior BRN-180 and the BRN-180S. The BRN-180S gas piston is adjustable from the front the gas block, making the switch to suppressor use quick and easy. The gas block vents excess gas to the front when suppressed, to ensure smooth cycling.
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 bolt replicates the original AR-180 bolt design, right down to its use of a standard AR-15 extractor.
The 10.5" barrel is machined from extra-strong 4150 carbon steel, with a hard Nitride finish that really resists surface wear. The BRN-180 is chambered in .223 Wylde - for extra flexibility in ammo choice - with 1-8" rifling, so it handles both .223 Remington and military-type 5.56mm NATO ammo with equal aplomb. 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 ½-28 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
- 10.5" barrel with matte black Nitride finish
- .223 Wylde chamber
- Button rifled bore; 1-8" twist
- ½"-28 threaded muzzle
- Replica 3-prong AR-180 flash suppressor
- Molded polymer ejection port cover
- Total weight: 4 lbs
Also brought over from the AR-180™ design is the ease of removing the BRN-180 upper's handguard. The recoil guide rods inside engage a U-clip that retains the handguard. When the bolt / carrier group is removed and the guide rods are pulled to the rear, the U-clip can be pulled down and the free-floating handguard assembly slid off! With some effort to retain a period look, our BRN-180 handguard has modern M-LOK® slots and a full length Picatinny top rail that matches seamlessly to the receiver's MIL-STD 1913 rail.
Big Book Catalog, Issue:72, Page:002