Exacting construction and rigorous durability are the standard for every weapon system that comes off BCM's line. BCM Professional Grade Weaponry are hard use tools, built to perform in combat where unfailing performance is the only standard for men and machine. Features: Upper receiver - receiver machined from aluminum forgings 7075-T6 and hardcoat anodized per MIL-A-8625F, type III, class 2 Upper receiver - M4 feed ramp flat top with laser T-markings Upper receiver - mid length gas system Upper receiver - BCM bolt carrier group Upper receiver - machined from Mil-Spec carpenter number 158 steel Upper receiver - HPT/MPI (high pressure tested/proof)/(magnetic particle inspected) Upper receiver - shot peened Upper receiver - tool steel extractor with BCM extractor spring Upper receiver - black extractor insert Upper receiver - chrome lined carrier (full auto profile) Bolt machined from Mil-Spec carpenter number 158 steel Chrome-lined bore and chamber, gas key Gas key hardened to USGI specifications steel extractor, black extractor insert Staked M4 lock nut Low shelf for RDIAS installation, accuwedge use