Powder residue, lead and bullet lubrication can get packed in your barrel's chamber, which can cause feeding and extraction malfunctions. Unfortunately, your .45 bore brush is the wrong diameter and usually too soft to remove chamber contamination. You need a Wilson "Chamber Cleaning Tool".  This tough little tool has a sturdy Delrin handle and very stiff stainless bristles to thoroughly clean your chamber. If you own a .45, you need this little tool.