Good gun cleaning starts on the inside, mainly in the bore--whether the gun is a shotgun, a pistol or a rifle. Whenever you shoot jacketed bullets in a rifle or handgun, a couple of dismal things begin to happen. First of all, as powder and copper fouling accumulate in the rifling, a decrease in accuracy begins to occur. After prolonged firing without cleaning, this loss of accuracy becomes quite measurable. Happily, a good cleaning almost always restores a barrel to its former accuracy. If the bore isn't cleaned promptly, however, something else ugly begins to happen.