You can tune all your ignition parts bearing surfaces and forget to do the channel liner and spring cups. This, alone, can cause you to have stacking and a rough feel if your spring cups are binding in the channel liner. Remember the channel liner and cups already fit snug when not in the gun. Punching the channel liner in the slide obviously will tighten this 'snugness'. It's an area of a trigger polish often overlooked and is essential for the 'complete' trigger polish.