For copper fouling I use Sweet's 7.62 and JB Bore Paste. For leading, in a .45 or 44 I use a 38 caliber bronze brush wrapped with bronze wool to make it snug in the bore. After a superficial cleaning of the bore with solvent, I dry the bore, then run the bronze wool through the bore. I run the rod through the bore from the muzzle, then screw in the brush from the other end. I then stroke the wool back and forth several times within the dry bore. Works great. Leading is often a symptom that there is something wrong with the bullet or the load. A good load won't lead if the barrel is decent.