MaximalPower Bronze Bore Brush 9&times;19mm Parabellum.357 Magnum / .38 Special .38 ACP (Auto) / .38 Super.357 SIG.380 ACP Caliber Firearms Great to remove what nylon bristles and cotton patches struggle with Brush Core Type: Aluminum. Brush Thread: 8-32 (Fits almost any rods or flex cables designed for cleaning) Bronze is strong enough to remove leading, but soft enough to not scratch steel bores