This DPMS Style 308 BCG is precision machined from 8620 Steel with a 9310 Precision Hard Ground Bolt. The entire carrier assembly is NiB, Electroless Nickel Boron coated with the patented, advanced UCT EXO process, unlike standard NiB coatings. This offers extreme lubricity with a friction coefficient of .02 and surface hardness of 82-85 Rockwell C.