NEXT LEVEL ARMAMENT NLX556 5.56 NATO PREMIUM BOLT CARRIER GROUP FOR AR-15 Whether you shoot for fun, hunting, or rely on your rifle for self defense, you want a reliable Bolt Carrier Group. The Next Level AR15/M16 Enhanced Bolt Carrier Group provides improved function and durability through several integrated improvements over other BCGs. Next Level produces each carrier from 4140ph steel to aerospace tolerances. The expanded rear diameter of the carrier allows for smooth cycling in the buffer tube. Next Level Armament use machined extractors , not cast, and they include a black insert and o-ring during assembly for reliable extraction. They ma Mfg: Next Level Armament