ACME 5.56 Mil-Spec Bolt Carrier Group AR-15 Nitride C158

This bolt carrier is manufactured from case hardened 8620 steel with properly staked 4130 steel gas key. The accompanying bolt is Carpenter 158, shot peened, HPT and MPI tested, and finished in a self-lubricating polished black nitride. Bolt lugs are CNC ground following heat treatment to insure the greatest accuracy possible.

Material: Carrier (8620 Steel), Bolt (C158)
Finish: Black Nitride. This advanced low friction coating minimizes the need for lubricants.
Gas Key: 4130 Steel attached with Grade 8 hardware and properly staked into a milled “valley” to ensure proper positioning.
Cam Pin: Hardened 4340 cam pin
Firing Pin: Mil Spec firing pin made of 8740 steel, center-less ground and Hard Chrome coated

Bolt Assembly: The Bolt is “true” Mil Spec dimension and external surfaces are CNC ground after heat treat for a precision fit.