3-Gun Competition AR 15 Upper Assembly. The Aero Precision Upper Receiver is a CNC Machine to exacting standard. We added our Ambidextrus Extended Charging Handle, making charging the gun much faster. The Bolt Carrier Group is made from case hardened 8620 steel and Black Nitride coated to increase service life. We then add the 1 MOA guaranteed ODIN 18” 3 Gun barrel, made from 416R Stainless Steel, with Rifle Length Gas and the proven 223 Wylde Chamber that works with 223 and 5.56 ammo. The gas system comes standard with the ODIN adjustable gas block that features 20 clicks of adjustment, Inconel adjustment screw, and black nitride finish that will last thousands of rounds. Bringing the upper all together is the ODIN 15.5” KeyMod Handguard. .