Tipton 13-Piece Rifle Bore Brush Set -This resistance is a bennefit over bronze brushes. The bristles are designed to be very ridged providing maximum bore scrubbing performance. Molded hinge top storage box included. Threads are industry standard: 8-32 on .22 cal through .45 cal. The .17 cal has 5-40 threads. Includes:17 Caliber (5-40 threads)22 Caliber20 Caliber (5-40 threads)35 / 9mm Caliber25 / 6.5mm Caliber375 Caliber243 / 6mm Caliber40 / 416 Caliber30 / 32 Caliber44 Caliber270 / 7mm Caliber45 Caliber50 Caliber