Rifle Firearm Aero Precision Bcm 300 Blackout, #300blk, 300 Aac Blackout, Semi-Automatic; 300 Blackout The BCM .300 Blackout is a firearm chambered in .300 AAC Blackout and manufactured by Bravo Company Manufacturing (BCM). This entry identifies the model and caliber for inventory, recordkeeping, or cataloging purposes. Configuration, barrel length, furniture, sights, and other features may vary depending on the specific model and factory or aftermarket components installed.