The Spike's Tactical M-16 (Full Auto) 5.56 Bolt Carrier Group is machined from 8620 Tool Steel. The carrier has MIL-STD-171 black phosphate finish inside and out with MIL-STD-171 hard chrome bore. The Spike's Spider logo is Laser engraved and is visable through ejection port door opening. All bolts are shot peened and are Individually High Pressure Tested (HPT) and then Individually Magnetic Particle Inspected (MPI). The bolt alone does not make your semi auto a full auto and is legal to own.