The Brass Core/Bronze Bristle Brush cleans the barrel completely. A brass core brush holds the bristles longer and can withstand frequent harsh use. Filled with superior over-sized bronze bristles that are larger than standard. They fit tighter and last longer. More bristles per inch on a Pro-Shot bore brush. Watch us out-clean the competition! Looped Brush End. The ends of our pistol, rifle, and shotgun brushes are looped, not sheared off like lower quality brushes. A looped end makes the brush superior and safer to use instead of a cut open end. Brass Coupling. Our brass coupling is made with precision threads to stay screwed into cleaning rods and will hold the brass core for long lasting tough use. What are the comparisons to Aluminum core brushes? A brass core brush holds the bristles longer and does not loosen and drop bristles out like aluminum core brushes. Aluminum core brushes bend easier and this causes the bristles to drop out. Most aluminum core brushes have sheared ends that can damage the bore and firing pin during use. Aluminum couplings bend easier with use. Therefore, if the coupling bends the core unwinds and bristles drop out. Most aluminum core brushes are undersized because they fail quickly when made at the correct size. That is often why you see a .270 Cal. Rifle brush that works for .270 Cal. and 7mm. It is not technically correct. Precision manufacturing and quality at its best! Pro-Shot’s famous “Benchrest Brush” is made caliber/mm/gauge specific to do the job right and for maximum cleaning power!