Founded to support the needs of Private Security Professionals working in theaters where durable mil-spec components for their weapon systems were not readily available, BCM (Bravo Company MFG, Inc.) builds professional grade weaponry manufactured, reinforced and tested to meet the unforgiving needs of professional Soldiers, Law Enforcement and responsible citizens in some of the most high threat environments in the world. Features: Threaded 1/2 x 28 in. for your 5.56mm carbine Machined from 4150 steel Phosphate coated per Mil-Std-171 Predrilled hole at the base for permanent installation When mounted per BATF specifications for a permanent installation it will bring your 14.5 inches M4 barrel to a non-NFA length of over 16.1 inches The A2X is predrilled and comes with a dowel pin and crush washer for installation