Angstadt Arms Bolt Carrier Group BCG .40 SW Black. Specifications for Angstadt Arms Bolt Carrier Group (BCG): Manufacturer: Angstadt Arms Color: Black Fabric/Material: 8620 Alloy Steel Gun Make: Glock Hand: Right Additional Features: Features removable weight for use with Law Tactical folding stock adapter Features: Machined from 8620 alloy steel with a QPQ black nitride finish For use with a standard AR-15 hammer Features removable weight for use with Law Tactical folding stock adapter Package Contents: Angstadt Arms Bolt Carrier Group Angstadt Arms AA40BCGNIT: Bolt Carrier Group .40 SW Black