LANTAC M-SPEC Bolt Carrier Group BCG 5.56x45mm NATO/.223 Nitride Finish 8620 Steel Black 01-MSPEC-556-NIT-EBCG. 56/.223 and 7.62/.308 Caliber the Lantac M-SPEC 5.56/.223 BCG is precision machined to milspec dimensions and tolerances. The carrier is...