Rise Armament RA1011NIB Bolt Carrier Group 5.56x45mm NATO Nickel Boron 4140 Steel
https://www.tandktactical.com/shop/851046006040-rise-armament-ra1011nib-bolt-carrier-group-5-56x45mm-nato-nickel-boron-4140-steel-15492
https://www.tandktactical.com/web/image/product.template/15492/image_1920?unique=d1130e2
RISE Armament advanced bolt-carrier group (BCG) manufactured with precision and individually inspected to ensure high-level performance.
