Bore Cleaning BrushesOur brushes are the best available. The bristles are phosphor-bronze. The diameter is precise and slightly over-sized. We suggest that you use a brush that is 1 caliber smaller than the bore of the firearm being cleaned, e.g., use a .277 brush in a .284 bore. Wrap a patch around the brush for a snug fit that does not allow the bristles to contact the surface of the bore. The bristles are softer than the barrel steel but the brush can carry salts and "crud" from primers and powder which can abrade the bore. The .17 adapter and the .22 cal brushes are for 7-32 thread. The larger brushes have 8-32 thread.