Blackpowder Products Breech Brush Set for Inline Rifles CVA’s breech brush set is used to loosen powder fouling. The large brush cleans breech area while the small brush cleans breech plugs. Blackpowder Products Breech Brush Set for Inline Rifles CVA’s breech brush set is used to loosen powder fouling. The large brush cleans breech area while the small brush cleans breech plugs.