The Faxon ARAK-21 Complete Upper (Faxon part no. URSSB556SSW) is a 16-inch, 5.56 NATO upper built around Faxon’s patented piston-driven operating system, finished in a limited-production Tungsten Cerakote on the receiver and handguard plate. Instead of running direct impingement gas into a buffer tube, the ARAK-21 uses a long-stroke gas piston with a self-contained recoil system, so it drops onto any standard mil-spec AR-15 lower with no buffer tube, spring, or permanent modification required. That eliminates the traditional buffer tube’s length constraint and opens the door to folding stocks and a fundamentally different operating feel than a standard AR-15 upper.

Key Specifications

• 16-inch barrel, chambered in 5.56 NATO.
• 1:8 twist rate.
• Piston-driven long-stroke gas system — no buffer tube required.
• Drops onto any mil-spec AR-15 lower with no permanent modification.
• Includes a Faxon MuzzLok ported brake.
• Finished in a limited-production Tungsten Cerakote on the upper receiver and handguard plate.
• Swappable between 5.56 NATO and 7.62×39 via separate Barrel Assembly Units.
• Semi-automatic action.
• 100% American made, backed by Faxon’s lifetime guarantee.

Frequently Asked Questions

Do I need a special lower receiver for this upper? No — the ARAK-21 is built to drop onto any standard mil-spec AR-15 lower with no permanent modification, buffer tube, or spring required.

Can I change calibers with this upper? Yes — Faxon’s ARAK-21 platform lets you swap between 5.56 NATO and 7.62×39 in minutes using separate Barrel Assembly Units.

What’s different about the ARAK-21’s operating system versus a standard AR-15 upper? It runs on a long-stroke gas piston with a self-contained recoil system instead of direct impingement, which eliminates the buffer tube and runs cleaner.

Buy the Faxon ARAK-21 16in 5.56 NATO Complete Upper, Tungsten Cerakote

Order the Faxon ARAK-21 16in 5.56 NATO Complete Upper, Tungsten Cerakote from a Lubbock, TX gun shop for fast, reliable shipping. Shop more FAXON FIREARMS gear or browse the AR rifles category at Schaefer Defense.