DOUBLE TAP ARMS 5.56 nitride MPI full-auto bolt carrier group.

Bolt is Magnetic Particle Inspected (MPI). 

8620 Full-auto profile bolt carrier group with 9310 steel bolt.

Gas Key Hardened to USGI Specifications, Fastened with Grade 8 screws, and Staked Per Mil-Spec.

Flag Engraved.

This BCG is for 5.56, and .300blk calibers.