MaximalPower Bronze Bore Brush .308 7.62&times;51mm 7.62x39mm Caliber Rifles Gun Cleaning Brushes copper 100% Imported Brush Bristle Type: BRONZE. Brush Core Type: Aluminum. Brush Thread: 8-32 (Fits almost any rods or flex cables designed for cleaning) Scrub all the tough to remove carbon, lead, & debris out of your bores. The bronze bristle are great to remove what nylon bristles and cotton patches struggle with.