Otis 6.5mm Bronze Bore Brush

A bronze bore brush is the part of a cleaning kit that does the scrubbing. This one is sized for 6.5mm bores, and the bronze bristles are soft enough to stay off the rifling while still breaking carbon and copper fouling loose from the grooves.

Bore brushes are consumables. Bristles lose their spring after enough passes and a tired brush pushes fouling around instead of cutting it, so most people keep spares in the range bag for the calibers they shoot most. Run the brush with solvent, follow it with patches, and let the patches tell you when the barrel is clean.