Last year, Brownells announced the addition of the BRN-180 side-charging upper receiver, and now they have a lower receiver to match.
The design of the BRN-180 was inspired by the Armalite AR-180 from the 1960s. The AR-18 was developed as a successor to the original AR-15/M16 design and the AR-180 was a semi-auto civilian version of the AR-18.
The BRN-180 incorporated many of the AR-18/AR-180 improvements, including its robust and reliable gas piston operating system. One of the biggest differences between the AR-18/AR-180 design and the AR-15 is that the former has recoil springs housed in the receiver instead of the AR-15′s more complicated buffer mechanism in the buffer tube and buttstock. This allows for the use of side-folding stocks, something the AR-15 platform cannot accommodate.
Like the original, 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.
Most importantly, Brownells designed the upper to be compatible with any standard, mil-spec AR-15 lower receiver. However, there’s always room for improvement when it comes to design and performance, so that’s why Brownells has now released lower receivers designed to work specifically with their BRN-180 uppers.
The BRN-180 lower receivers do away with the traditional receiver extension threads, and in their place have a milled-in Picatinny rail section for mounting of stocks or braces.
The receivers are made from billet 7075 T-6 aluminum with a hard-anodized finish, have an integral oversized trigger guard, and the unique features of a threaded bolt catch pin and captive set screw for the takedown pin detent spring.