This is a great tutorial on how to polish the parts on your Glock. It is a relatively inexpensive way to create a smooth recoil, and smooth working parts. Here are a few reasons that might interest you in polishing your Glock parts.
1) Carbon doesn’t stick as bad after a day at the range. (Easier To Clean)
2) The polished parts move with less resistance giving you a smoother trigger pull.
3) You don’t need to spend hundreds of dollars on a new trigger to get similar results.