ARAK-21 Caliber Conversion Kit – Complete w/ Bolt & Firing Pin

Note- This kit is appropriate for an ARAK owner who does not have the bolt for their new caliber. Of note, 5.56 and 300 BLK are interchangeable. 7.62×39 has its own bolt. For just the BAU, see the BAU Only product listing. 

Kit Includes:

• BAU of Customer’s Choice
• Complete ARAK-21 Bolt
• Firing Pin

ARAK-21® Barrel Assembly Unit Technical Description.

•  -The ARAK-21® Barrel Assembly Unit (BAU) is comprised of the barrel, barrel trunnion, gas block, gas tube, gas adjuster, and the muzzle brake.
• -Barrels are made from resulphurized 4150 CMV GBQ (Gun Barrel Quality) MIL SPEC mil-B-11595-E Pre Heat Treated 28 – 32 Rc Steel or 416-R Stainless Steel

-All ARAK-21® barrels are manufactured at Faxon Machining in Cincinnati, OH. 

• -All barrels are gun drilled, gun reamed, and button rifled.
• -All barrels are nitrided using a Quench / Polish / Quench (QPQ) process.
• -Barrels are currently available in 12 ½”, 16”, and 20” lengths. (12.5 & 16″ for 7.62×39)
• -Barrels are currently available in both .223 /5.56 Caliber 1 in 8 twist, and 300 BLK & 7.62×39 caliber barrels in 1 in 8 twist.
• -5.56 caliber barrels are threaded with a ½” – 28 UNF thread at the muzzle.
• -300 BLK & 7.62×39 barrels are threaded with a 5/8” – 24  UNF thread at the muzzle.
• -Each gas block and gas adjuster knob has four settings,  three allowing variable gas flows and one blocking gas flow for single shot operation.
• -The 5.56 & 7.62×39 gas adjuster knob is inserted and removed by rotating into position and either pushed or pulled.  There are detents to identify the 4 gas selections. 300 BLK has three settings: low, high, and off.
• -The BAU is connected to the upper receiver with “Keys” and is held in place by the pivot pin, and the lower forearm.
• -The gas block on the ARAK-21® BAU has a clean out port between the gas cylinder, and the barrel.
• -300 BLK & 7.62×39 Caliber BAU’s have a unique profile on the barrel forward of the gas block to identify the caliber by both sight and touch.
• PLEASE NOTE:Images shown may include items not sold with the ARAK-21® Upper Receiver.

Faxon Technical Note on 7.62×39 Caliber Kit:

• The factory recommends a high-power hammer spring to use with the 7.62×39 kit.
• Many aftermarket “light” triggers will not reliably ignite 7.62×39 surplus ammunition.
• A spring is included and installed on XRS rifles ordered with the caliber. It is sold separately for the upper or caliber kit only.
• Faxon offers a Wolff high power spring for sale.
• Faxon recommends HiperFire triggers with a special spring kit for an improved trigger pull. Contact HiperFire for details.

300 BLK Compatibility:

Due the fixed gas system length of the ARAK platform and variability of 300 BLK subsonic ammunition, a suppressor is required for reliable function with the 300 BLK BAUs using subsonic ammunition and supersonic on the 12.5″ barrel.