If you have a Kel Tec SU-16, you might love it except for one little detail… The takedown pin in the handle is so tight that you need a tool to insert or remove it. I found a great hack on what to do about this.
You can replace the takedown pin with a 1/4″ hitch pin from a hardware store. It works peachy keen. The pin stays in perfectly and is easy to remove by pulling on the attached ring. (Source)