Over the last few years I've seen some gun companies turning their platforms inside out (in some cases literally) in order to produce an AR-15 with a folding stock. Some of these folding options will fire with the stock folded while others will not. There are designs that even go so far as to expose the inner workings of the rifle when folded, which seems problematic for use in dirty conditions.
Rather than developing something new, Brownells has tackled the AR folding stock problem by revisiting an existing, if somewhat forgotten, design and giving it a modern twist with the new BRN-180 upper assembly.
Based on the original 1960s era AR-180, this upper employs a robust short-stroke piston system, a three prong flash hider, a reciprocating side charging handle and a twin internal guide rod system replacing the typical AR buffer assembly. This upper has been configured to drop onto any mil-spec AR-15 lower assembly with desirable modern updates including a .223 Wylde chamber, 1:8 twist rifling, and an easy to remove M-Lok handguard.
Manufactured with completely new materials and thoroughly-modern methods, this upper has a suggested retail price of $799, making it one of the most affordably priced piston driven options currently on the market. Look for the BRN-180 upper listed under product number #078-000-483 on the Brownells website.