ARAK-21 Gas-Piston Upper Receiver for AR-15 Lowers from Faxon Firearms
The ARAK-21 is a long-stroke gas-piston system that seems to borrow design features from both the AK and the AR designs. The piston system is simple, rugged, adjustable, and reliable. The gas regulator (adjuster) has four positions; three for functioning under various conditions, and another setting that shuts the gas off completely, rendering the weapon a manually-operated rifle. The ability to adjust the amount of gas used to operate the weapon allows it to function reliably if dry, dirty, using weak ammunition, or with a sound suppressor.
The ARAK-21 upper attaches easily atop a mil-spec AR-15 lower, using the pivot pin and the rear take-down pin, just as with any AR rifle. The ARAK-21 does not use the buffer tube spring to return the bolt carrier into battery. Instead, the ARAK has its own recoil spring contained in the upper receiver. This allows the weapon to use standard AR-15 buttsocks, no buttstock, or a hinged folding buttstock, offering a lot of versatility in weapon configuration.
The upper receiver of the ARAK-21 is machined from 6061-T6 billet aluminum and incorporates a full-length 1913 Picatinny rail. The unit shown here is finished in a matte black, but more colorful versions are offered, if desired. The handguard/forearm also has sections of Picatinny rail positioned at three, six, and nine o’clock, and each of these rail sections are removable, if desired. The handguard/forearm is machined integrally with the receiver for exceptional strength and rigidity. The ambidextrous charging handle is located alongside the forward portion of the upper receiver, is spring loaded, and does not reciprocate with the bolt carrier. The handle can be easily switched from the left to the right side, if desired. The ARAK-21 upper can also be purchased in a left-hand version, and the bolt can be turned 180 degrees for LH ejection.
One interesting and useful feature of the ARAK-21 is that it is very easy to switch from 223/5.56mm to the 300 Blackout chambering just by switching the barrel unit. The barrels are button-rifled, and are offered in both medium and heavy profiles. Switching from one caliber to the other takes about two minutes, and the only tool required is an Allen (hex) wrench. Loosening six captured screws along the bottom of the forearm removes that section of forearm, and the barrel unit slides forward and off the weapon. Installing the extra barrel unit is just as easy, and the 300 Blackout uses the standard 5.56mm magazine, which is cheap and plentiful at this time. The 300 Blackout uses a different recoil spring as well, and switching the spring takes less than one minute, and requires no tools. The 4150 chrome-molly barrels are offered in lengths of 12.5, 16, and 20 inches. The 5.56mm and 300 Blackout barrels are threaded 1/2x28 and 5/8x24, respectively, for the attachment of suppressors or other muzzle devices. The barrels are supplied with the gas system and a muzzle brake installed. The 223/5.56 barrels are button-rifled with a one-in-seven-inch twist, and the 300 barrels have a one-in-eight-inch twist.