Spikes ST5BG03 Bolt Carrier Group 223 Rem/5.56x45mm NATO Nickel Boron AR-15/M16 Full Auto

The Spikes ST5BG03 is a Mil-Spec bolt carrier group for 5.56x45mm NATO and 223 Remington AR-15 and M16 pattern rifles. Every BCG is High Pressure Tested and Magnetic Particle Inspected (HPT/MPI) for verified quality. The carrier is machined from 8620 tool steel and paired with a 158 Carpenter steel bolt, then coated inside and out with Nickel Boron on the bolt, carrier, and gas key for a smoother surface than hard chrome, easier cleaning, faster cycling, and extended lube-free operation without chipping, peeling, or flaking.

The forged Mil-Spec gas key is attached with Grade 8 hardware and properly staked. The bolt is shot peened for durability and uses a shrouded firing pin, Mil-Spec extractor spring, black extractor insert, Viton O-ring, and tool steel extractor. This full-auto profile BCG drops into any standard AR-15 upper receiver and runs in semi-auto AR-15s. Please note: installing a full-auto BCG does NOT make a semi-automatic rifle fully-automatic.