The ALG Black Nitride Mil-Spec Bolt Carrier Group (BCG) is a great upgrade for your current AR or a perfect starting point for your next build. Black Nitride is an advanced low friction coating that minimizes the need for lubricants. The Bolt is CNC ground after heat treat for true Mil Spec dimension’s and fit. Made of case hardened 9310 steel, shot peened, and ships with the Crane O ring installed. Our bolts are High Pressure Tested (HPT) and Magnetic Particle Inspected (MPI).
The Carrier is made of 8620 steel, the gas key is 4130 steel and is attached with Grade 8 hardware and properly staked. The ALG Black Nitride BCG is compatible with AR15 rifles chambered in .223/5.56, and .300 Blackout