LanTac USA LLC Enhanced M16 Bolt Carrier Group, .223/556NATO, Nickel Boron Coated LA00223 Lantac's new BCG is precision machined from 8620 Steel with a shot peened bolt manufactured from Carpenter 158 and Magnetically Particle Inspected. 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.