Nylon bore brushes are the best choice for your routine gun cleaning. For some deeper cleaning it is advised to use a brass bore brush with some solvent and patch. You should consider using a bronze bristle bore brush only when you want to clean a heavily fouled or completely grimed bore that’s tough to clean. When using a bronze brush make sure that you do not use it with a copper solvent as it can eat up the material. If you want to use copper solvent, use only nylon brushes for cleaning.