Blank Adapter for the M1918 Browning Automatic Rifle. Made from 4140 Pre-hardened rod for long life it is internally threaded and shouldered for 3/8 NC aperture screws. The aperture screws tighten against the BFA and not the crown of your barrel. Finished in a durable, hot blued finish. Fits Ohio Ordnance Semi Auto SLR's as well as Original USGI BAR barrels.