MaximalPower Bronze Bore Brush 22 Long Rifle.222 223 Remington, 5.5x45mm NATO, 5.45x39mm, FN 5.7x28mm & Other 5.56mm/0.22" Sized bores 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