Bore Cleaning Brushes - Sold Each. You will find that the brushes produced by OTIS will give you many times the life of most brushes. These brushes have a Tufcor® proprietary core wire that is corrosive resistant, has a tighter twist for better bristle retention, and can be used with all firearm cleaning chemicals. Otis premium bore brushes have twice the fill as other brushes, the stem is cold welded to the core, and the brushes are filled to the end. Each brush has the specific caliber or gauge stamped on the stem.